Nghiên cứu hiệu quả giữ nước của rừng phục vụ chi trả dịch vụ môi trường đối với hồ thủy điện ở việt nam tt tiếng anh

MINISTRY OF EDUCATION AND TRAINING MINISTRY OF AGRICULTURE AND RURAL DEVELOPMENT

VIETNAM NATIONAL UNIVERSITY OF FORESTRY

NGUYEN PHUC THO

RESEARCH ON WATER RETENTION EFFICIENCY OF FOREST
FOR PAYMENT FOR ENVIRONMENTAL SERVICES FOR
HYDROPOWER RESERVOIRS IN VIETNAM

SUMMARY OF DOCTORAL DISSERTATION
Major: Silviculture
Code: 9.62.02.05

HA NOI - 2020
1


The dissertation has been completed at:
VIETNAM NATIONAL UNIVERSITY OF FORESTRY

Supervisors:
1. Assoc. Prof. Dr. Tran Quang Bao
2. Assoc. Prof. Dr. Nguyen Dinh Duong

Examiner 1:………………………………………………………………
Examiner 2: ………………………………………………………………
Examiner 3: ………………………………………………………………

The dissertation will be defended before the University Board of Examiners
Venue: Meeting Room E, Building A3

Vietnam National University of Forestry, Xuan Mai, Chuong My, Ha Noi
Time: At………… Date……… Month……. Year 2020

2


LIST OF PUBLICATIONS

1. Nguyen Phuc Tho, Tran Quang Bao (2011). The potential and solutions to
increase ecological economic values of natural forest in Vietnam. Journal of
Economic Ecology Vol. 38/2011, page 111- 117.
2. Nguyen Phuc Tho, Tran Quang Bao (2017). Evaluate the water retention
efficiency of forest in hydropower reservoirs by bio-physical indicators. Journal
Agriculture and Rural Development, Vol. 11/2017, page, 116-124.
3. Nguyen Phuc Tho, Tran Quang Bao (2017). Determining the value of forest
environmental services for hydropower reservoirs in Vietnam. Journal
Agriculture and Rural Development, Vol. 15/2017, page 145-152.
4. Nguyen Phuc Tho, Tran Quang Bao, Nguyen Hong Hai (2019). Flow
Characteristics of Hydropower Reservoirs in Vietnam. Journal Agriculture and
Rural Development, Vol., 07/2019, page 130-136.

3


TABLE OF CONTENTS

Page
TABLE OF CONTENTS
1
INTRODUCTION

6
1. Significance of the Study .............................................................................. 6
2. Objectives ...................................................................................................... 6
2.1. General objective
6
2.2. Specific objectives
6
3. The research object and scope of the study .................................................. 6
3.1. Object of study
6
3.2. Scope of study
6
4. New contributions of the study ..................................................................... 7
4.1. The theoretical and scientific basis
7
4.2. The results and conclusions
7
4.3. The practice
7
5. The general structure of the dissertation ....................................................... 7
CHAPTER 1 LITERATURE REVIEW
8
1.1. Some related concepts ................................................................................ 8
1.2. National and international research situation ............................................. 8
CHAPTER 2. RESEARCH CONTENTS AND METHODS
9
2.1. Research contents ....................................................................................... 9
2.1.1. Study on characteristics of basins
9
2.1.2. Determining water retention capacity for hydroelectric reservoirs

in the dry season
9
2.1.3. Determining the water retention value range of forests in
hydropower reservoirs
9
2.1.4. Proposal the amount of payment for forest environmental services
for hydropower plants
9
2.2. Methods ...................................................................................................... 9
2.2.1. The methods of data collection
9
2.2.2. Methods of data processing
14
CHAPTER 3. RESULTS AND DISCUSSIONS
15
3.1. Characteristics of the basins ..................................................................... 15
3.1.1. Characteristics of the observed basins
15
4


3.1.2. Some characteristics of forest and forestland states related to water
flow in basins
16
3.2. Water retention capacity of the forest for hydropower reservoir in the dry
season .......................................................................................................... 16
3.2.1. Water retention capacity of the forest for hydropower reservoir in
the dry season
17
3.2.2. Water retention per hectare of forest

18
3.2.3. Water retention of forest per kWh of electricity
18
3.2.4. Water retention of forest per cubic meter of water
18
3.3. The monetary value of water retention efficiency of forests ................... 19
3.3.1. Correction coefficient
19
3.3.2. Range of water retention value of the forest
19
3.3.3. Range of water retention value per hectare of forest
19
3.3.4. Range of water retention value per kWh of electricity
20
3.3.5. Range of water retention value of forest per one cubic meter of
water
20
3.4. Proposal the amount of payment for forest environmental services for
hydropower plants ....................................................................................... 20
3.4.1. Principles for determining the number of payments for forest
environmental services
20
3.4.2. The estimation of the range of payment for forest environmental
services for hydropower plants per kWh of electricity
20
3.4.3. The estimation of payment for forest environmental services for
hydro-electricity per hectare of forest
21
CHAPTER 4. CONCLUSIONS
23

4.1. Conclusions .............................................................................................. 23
4.2. Existence and recommendations .............................................................. 24

5


INTRODUCTION
1. Significance of the Study

Payment for forest environmental services has contributed greatly to
raising social awareness about the value of forest environment, benefits, rights
and obligations of those who are paid and have to pay (both of payee and
payer).
The policy of payment for forest environmental services (PFES) has
been applied effectively in life and has brought many positive aspects.
However, the implementation of PFES policy has not been thoroughly
resolved, the determination of PFES value and level is still not scientific and
not sufficient to convince PFES users as well as forest owners. The scientific
basis for determining the value of PFES directly affects the effectiveness of
the advocacy and policy implementation process. The lack of basis leads to
reduction of the policy value of the forest environment.
So far, although there have been legal documents issued and applied in
practice; there is no detail, specific and comprehensive research confirming
the exact role and value of keeping the water of the forest to satisfy the parties
involved in PFES, especially PFES for hydropower reservoirs. From the
urgent issue, the topic “Research on water retention efficiency of forest for
payment for environmental services for hydropower reservoirs in Vietnam"
is conducted as necessary, great scientific and practical implications."
2. Objectives
2.1. General objective

Supplementing the scientific basis for completing the policy on PFES.
2.2. Specific objectives

1- Determining the water retention value of the forest in the hydropower
reservoir area.
2- Establishing the range of water retention value of the forest as a basis
for proposing the amount of PFES.
3. The research object and scope of the study
3.1. Object of study

The research object of the study is the ability of forests to retain water
in some hydroelectricity plants in Vietnam.
3.2. Scope of study

- Spatial scope: The study space was conducted with 66 hydropower
reservoir basins in Vietnam.
- Temporal scope: The data was collected in the basins in 2012 and
2013
- Content: The study focuses primarily on the value of forest
environmental services through the role and ability to retain water in
6


the dry season for hydropower plants.
4. New contributions of the study
4.1. The theoretical and scientific basis
- Supplementing the scientific basis for the selection of methods to
study the water retention capacity of forests;
- Contributing to providing a scientific database of policies for payment

of forest environmental services in hydroelectric lakes in Vietnam.
4.2. The results and conclusions
- Identify characteristics of basins;
- Identify the role and value of water retention of forests in the dry
season;
- Establish a range of the amount of forest water retention services
according to forest origin, forest types and forest status in hydropower
reservoirs;
- Propose the amount of PFES for some hydropower plants in Vietnam.
4.3. The practice
Supporting managers in planning and calculating the amount of PFES
in compliance with local conditions to improve the effectiveness of forest
protection and development in Vietnam.
5. The general structure of the dissertation
The outline of the dissertation as following:
- Along with the introduction, the main part is presented, including 3 chapters:
+ Chapter 1: Literature review
+ Chapter 2: Research contents and Methods
+ Chapter 3: Results and Conclusions
- References including English documents and Vietnamese documents;
- 38 tables are numbered in order; and
- 18 images are numbered in order.

7


CHAPTER 1
LITERATURE REVIEW

1.1. Some related concepts

The dissertation cited relevant concepts through legal documents. Such
concepts include (1) Forest environment; (2) Forest environmental services;
(3) Payments for forest environmental services; (4) Water retention capacity
of the forest.
1.2. National and international research situation
In this section, the dissertation has summarized all the national and
international research on issues related to the study including: (1). Amount of
forest value; (2). Water retention capacity of the forest (including conditions
affecting water retention capacity of the forest, mechanism of them,
evaporation and flow characteristics in basins); (3) Payment for forest
environmental services.

8


CHAPTER 2.
RESEARCH CONTENTS AND METHODS
2.1. Research contents
2.1.1. Study on characteristics of basins
2.1.2. Determining water retention capacity for hydroelectric reservoirs in the dry
season

- The effect of water retention on forest per hectare;
- The effect of water retention on forest per kWh;
- The effect of water retention on forest per cubic meter of water;
2.1.3. Determining the water retention value range of forests in hydropower
reservoirs

- The water retention value range of forest per hectare;
- The water retention value range of forest per kWh;

- The water retention value range of forest per cubic meter of water.
2.1.4. Proposal the amount of payment for forest environmental services for
hydropower plants

- Principles for determining the payment rates for forest environmental
services;
- Proposal for payment of forest environmental services for hydropower
plants;
- Determine the payment rates for forest environmental services for
hydropower plants.
2.2. Methods
2.2.1. The methods of data collection

2.2.1.1. Research methods of hydrological indicators
In the world, there are three main groups of methods to study
hydrological indicators in relation to influencing factors. In this topic, the
dissertation uses research methods on many basins that are not similar.
2.2.1.2. Identify biophysical criteria
To study this content, the topic has experimented with 6 methods that
have been and are being applied in practice, including Method using test
yards, method using wooden stakes, method using erosion barrier, method of
using erosion trap, method using hydrographic observation station and
method using mathematical model with eight evaluation criteria for each
method. In which, there are some important criteria that are evaluated by
weight factor. Based on that, the study has selected the most optimal and
effective method, which is the method using the hydrographic observation
station with the highest total evaluation score.
This method is implemented as follows: Constructing hydrographic
stations to investigate the flow in the output section of many basins with
different characteristics, thereby analyzing the effects of vegetation cover and

9


factors to the water output at the point of discharge of the basin.
(1). Information needs to collect
a. The general information:
General information includes boundary, area, elevation, the average
slope of the basin, area of forest status, precipitation transported in the basin,
flow and sediment of 66 basins (including 17 basins with national observation
stations) distributed in regions across the country.
Area and boundary of basins: The research basins have boundaries and
areas that are entirely within the territory of Vietnam. The boundaries of the
research basins are determined by the Digital Elevation Model (DEM) with
the help of ArcGIS software and verified by analyzing the distribution of
contour lines on the 1: 50000 topographic map.
The area of the basins is determined by the map boundary and the
CartesianArea function of Mapinfo software.
- The average elevation of the basin: the average elevation of the basin is
determined by the Digital Elevation Model (DEM) with an equal distance
between elevation points of 30m.
- The average slope of the basin: the average slope of the basin is also
determined through the DEM model and the slope function of ArcGIS
software follows these steps: Spatial Analysis Tools  Surface  Slope.
- The area of forest status in the basin: for small and medium basins
where flow and sediment flow were directly investigated in 2012, 2013, this
forest status map is reviewed and supplemented by using LANDSAT 8
satellite image with a resolution of 15m. Landsat satellite images are free to
download at the website: The area of the
forest statuses in the basin is determined on the forest inventory map for the
period of 2013 - 2016 published by the Ministry of Agriculture and Rural

Development.
- Precipitation:
Precipitation is measured by udometer in 49 basins without a national
monitoring station along with the flow and sediment monitoring periods. The
location of the measuring station shall not exceed 2 km from the point of
measurement of flow and sediment.
Measurement time: at 7 o’clock and 19 o’clock daily (a new day from
19 o’clock)
- Flow, the height of water level:
Concrete sluices (cylindrical and box) with the system of blocking soil
and sediment to stabilize the flow.
Time of investigation:
For temporary observation stations, the survey time is conducted once or
10


twice depending on the weather of the survey. Specifically,
+ Investigate 1 time on a sunny day at 7-8 o’clock, 2 days after rain;
+ Investigation 2 times: a rainy day at 7-8 o’clock and 17-18 o’clock,
less than 2 days after the rainy day. The time for measurement is from 46 to
76 days during the transition period from the beginning to the middle of the
rainy season.
The height of water level: is determined by the measure of water before
and after the sluices.
Flow rate: measured by foam float, drifting from front to back of drain,
made three times in a row for each survey point.
For 17 basins have national observation stations:
The hydrographic survey at national hydrographic stations is conducted
according to the general procedure which is twice a day at 7 AM and 7 PM.
For this content, the dissertation has monitored the flow in 49 basins and

used the flow monitoring data of the Vietnam Meteorological and
Hydrological Administration in 17 other basins. The observed data for the
national hydrographic stations are for the whole year 2007, with other stations
starting from July or August and lasting from 1.5 to 2.5 months in 2012 and
2013. This is the transition period from the beginning of the rainy season to
the highest rainfall period of the year. The catchment areas range from a few
hectares to hundreds of thousands of hectares.
b. Methods for determining the amount of water retained by the forest
during the dry season
- Determine the flow volume for 6 months in the dry season:
In this study, each hydrological station is considered an outlet point to
collect water from a hydroelectric reservoir. The amount of water through the
hydrographic monitoring station is determined by analyzing the process flow.
Based on the rainfall distribution by months of the year, it is possible to
determine the dry season months for each place (6 consecutive months with
the lowest rainfall).
- Determine the total amount of additional flow due to the forest:
Using empirical equations with impact factors to calculate the total
amount of water for different forest cover levels will determine the total
additional flow due to the influence of the forest.
- Determine the standard forest area:
The standard forest area and the area ratio are determined according to
the water holding capacity of forest statuses.
The standard forest area is the forest area that has been modified to retain
water equivalent to the status with the highest water holding efficiency natural forest.
11


- Develop empirical equations related to dry season water amount with
influencing factors:

The relationship between the dry season water amount and influencing
factors was built through statistical analysis of data collected at 66
hydrographic stations on the total flow of the dry season, catchment area,
elevation, slope, precipitation, and forest cover rate in the basin.
- Determine the number of cubic meters of water retained by the forest that
supplies the flow during the dry season:
The number of cubic meters of water retained by the forest for supply
during the dry season is determined by changing the standard forest cover
from 0 to 100% in the empirical equation between these quantities and the
influencing factors.
c. Converting the value of forest environmental services in the hydroelectric
area from biophysical criteria to money
Using the market price method: the value of the forest water holding
service is calculated by the amount of water retained by the forest for
hydroelectricity in 6 months of the dry season multiplied by the water price of
the irrigation charge.
d. Study on the method of determining the adjustment coefficients of
payment for forest environmental services K
Determine the coefficient K for payment of forest environmental
services based on forest origin, rich and poor level, protection level by the
comparative method. Accordingly, the coefficient K of a forest status will
be determined by the ratio of the environmental value of the forest state to
the environmental value of the forest status with the best environmental
efficiency.
The coefficient K will be determined individually according to each
criterion that affects decisively on the value of forest environmental services,
including forest type (protection forest, special-use forest, etc.), forest origin
(plantation forest or natural forests), forest status (rich, medium or poor
forests, etc.). For a specific forest plot, there will be 3 adjustment coefficients
of payment for forest environmental services: K1 by forest type, K2 by forest

origin and K3 by forest status.
(1). Principle of determining the coefficient K
The principles for determining the correction factor K are as follows.
+ The coefficient K must change according to the environmental
efficiency of the forest.
+ The coefficient K must be easy to apply in practice.
+ The coefficient K should support the promotion of community rights
and responsibilities sharing in forest protection and development.
12


+ The coefficient K is determined by the comparative method
+ The coefficient K is determined by the index related to environmental
efficiency
(2). The criteria for determining the coefficient K
The used criteria for determining the coefficient K are forest type and
status.
(3). The index used to determine the coefficient K
The index used to reflect the value of services is an indicator of the water
retention capacity of the forest (W).
e. Method of determining the value of forest water storage service for
hydroelectricity per ton of land, one cubic meter of water and one kWh of
electricity:
The value of forest water retention per cubic meter of water is defined as
25% of the unit price of electricity sold with the amount of power generated
by the plant from one cubic meter of water.
The water retention value of forests per kWh is determined by dividing
the total value of water retention service by the total electricity output of
hydroelectricity generation facilities.
2.2.1.3. Establish a range for the value of forest environmental services for

hydropower generation facilities in the study basins
The value of forest environmental services for each kWh is determined
by dividing the total value of forest environmental services by the commercial
power output of the plant.
The value of forest environmental services calculated per cubic meter of
water is determined by dividing the total value of forest environmental
services by the total cubic meters of water provided by the forest during the
dry season for the hydroelectric plant.
The value of forest environmental services for a hectare of forest is
determined by dividing the total amount paid for forest environmental
services by the standard forest area in the basin.
2.2.1.4. Determine the range of payment rates for forest environmental
services for hydropower generation facilities nationwide
In order to determine the framework for payment of forest environmental
services to hydropower generation facilities nationwide, the empirical
equation reflects the relationship of natural and socio-economic factors with
the value of forest environmental services and the payment of forest
environmental services are established. Based on that, we define the range of
payment rates for forest environmental services per hectare of standard forest
and per kWh of electricity. In order to develop empirical equations, the
calculated data in the basins and comparative methods are applied through
13


changes in the value of water retention services of forests, changes in K
coefficient, change the level of payment per hectare of forest and the level of
payment per kWh of electricity according to natural and economic and social
factors.
2.2.2. Methods of data processing
The collected data is processed by appropriate statistical software.

Through analysis, processing, and calculation, the thesis has implemented a
number of specific steps:
- Determine the standard forest area;
- Converting the value of forest environmental services in the
hydroelectric area from biophysical criteria to money;
- Determine the adjustment coefficient for payment of forest
environmental services K.
- Determine the value of water retention service for hydroelectricity of
one hectare of a forest with the payment adjustment coefficient K;
- Calculate the value of water retention service for hydropower of a
hectare of a forest with the composited K factor of 1;
- Determine the amount of payment for a forest plot for water retention
services.

14


CHAPTER 3. RESULTS AND DISCUSSIONS
3.1. Characteristics of the basins
3.1.1. Characteristics of the observed basins

3.1.1.1. General characteristics
The results showed that the characteristics of the research basins as
follows:
+ Research basin characteristics are relatively diverse: with a basin area
ranging from a few hectares to a hundred thousand hectares. The height of
catchment points of the basins ranges from 87 to 1081m, an average of 422m.
The average slope in the basin is from 3 to 30 degrees, the average is 19
degrees.
+ The proportion of forest area in basins has large fluctuations:

The area of natural forests, planted forests as well as the forest area in
general in basins fluctuates to a great extent. Forest area ratio ranges from 0 to
100%, an average of 63%.
3.1.1.2. Flow rate
The results show that the flow rate in the basins varies from a few m3/s
to hundreds of m3/s. The maximum flow rate (qmax) is 3 to 30 times higher
than the average flow rate (qtb), an average of 13 times. The lowest flow rate
(qmin) ranges from approximately 0 to tens of m3/s. The analysis of the
characteristics of flow changes in the basins gives some conclusions:
3.1.1.3. Relationship between total flow and total rainfall
The total flow is closely related to the total rainfall that precipitated into
the basin.
On average, the total flow is about 0.82 times the total rainfall. The
relationship of the total flow with the total rainfall is very tight by the linear
equation y = 0.7733x-5.0956 (R2 = 0.97). Thus, the total flow depends mainly
on the total rainfall.
For 17 basins with observable data for the whole year, the ratio of the total
flow to the total annual rainfall is:

The average annual rainfall in these basins is 2257mm, which corresponds
to 573 mm of rainfall spent on evaporation in a year, averagely a month is
47.7mm, and averagely a half of year is 286.6mm.
3.1.1.4. The relationship between the total flow and the total rainfall that
falls into the basin
The results of the relationship analysis show that:
- The average flow rate, the highest flow rate and total flow (Qdc) are
closely related to the total rainfall in the basin with the correlation coefficient
in the order of R2 = 0.96 and 0.92. The correlation coefficient between the
15

flow rate and the total amount of rainfall in the basin is greater than 0.85,
except for the lowest flow (R2 = 0.5).
- The relation of the lowest flow rate (or dry season flow) to the total
rainfall is not as close as the relation between the highest flow rate and the
average flow rate with the total rainfall.
3.1.1.5. Relationship between flow rate and slope
The relationship between the lowest flow rate and the total rainfall is
always lower than its relationship with both the total rainfall and slope, the
correlation coefficient R increases from 0.82 to 0.89.
The lowest flow rate is closely related to the total rainfall and the average
slope of the basin. The larger the average slope of a basin, the higher the lowest
flow rate.
3.1.1.5. Rainfall and flow characteristics by months of the year
The results show that in the tropical conditions of heavy rainfall in
Vietnam, the total flow is directly dependent on the total rainfall. Up to 97%
of the total flow directly depends on the total rainfall.
The amount of water through the hydrological monitoring station is
considered the amount of water accumulated to a hydropower reservoir where
the dam is located at the hydrological station, which is determined by
analyzing a chart of rainfall changes by months in a year.
The data show that the rainy season in different localities sooner or later,
but all last on average 6 months.
The rate of rainfall in the dry season compared to the total rainfall in the
basins reaches from 3.2 to 25.4%. Meanwhile, the ratio of dry season flow to
total flow is from 13-36%.
3.1.2. Some characteristics of forest and forestland states related to water flow in
basins

Calculation results show that for the forested state in the study area

(through 177 OTC) shows:
+ The tree height reaches an average of 12.8m, values from 8.3 to 15.6m
with the biggest fluctuations being in the state of restored and planted forests
of acacia mangium (4.0 and 4.5m ).
+ The average canopy cover in the forest states (excluding the states
without forest covers such as shrubs and upland fields) is from 26.0 to 63.4%
with standard errors from 7.1 - 19.8%.
+ Forest coverage is from 41.0 to 71.8%.
+ The percentage of dry litter in the studied forest areas in each forest
status has a value ranging from 36.0 to 78.9%.
3.2. Water retention capacity of the forest for hydropower reservoir in the dry
season

16


3.2.1. Water retention capacity of the forest for hydropower reservoir in the dry
season

3.2.1.1. Determining the conversion coefficients that are different from
standard forests
3.2.1.2. Standardized forest area in the basins
3.2.1.3. Relationship between dry season flow module and some basin
characteristics
The analysis results show that the total dry season flow per 1 ha, also
known as dry season flow module (Mk), is relatively closely related to the
index K = ((Lm) × (Doc)0.5 × (TLRQD1)),
The indicator of forest cover rate is a factor that makes up the index
K. Thus, the effect of the standard forest rate on the dry season flow is
uniform. The higher the percentage of standard forest covers, the greater

the dry season flow module.
Among the three factors that most significantly affect the flow in the dry
season of the basin, the two factors of precipitation and the average slope of
the basin are little changed, and the remaining factors belong to easily
changing biological characteristics that are the standard forest cover rate.
The empirical equation for dependency is:
Mk = 0.0061 × K1 × (K2 + K3) + 344
+ The efficiency of water retention of forests increases according to the
forest coverage rate.
+ The efficiency of water retention of forests increases with rainfall and the
average slope of the basin.
The dissertation used the above empirical equations and data on area,
average slope, forest cover rate, rainfall, amount of water provided by the
forest during the dry season in 32 hydropower reservoirs with basin in interprovince that has identified the average annual dry season flows from one
hectare of the basin in the current forested condition, the average dry season
flow from one hectare of the basin in the non-forested area deviations from
the total dry season water flow between the forested and non-forested
watersheds in the basin and the average dry season flow from a hectare of
standard forest. The results show that the differences in the standard forest
cover rates, the average slope in the basins and the average rainfall in the
basins have made the average water retention efficiency of each hectare of
forest different. ranging from 1,839 to 4,565m3/ha. In the North, an average of
1 ha of forest holds 3,162 m3/ha of water to provide hydroelectricity in the dry
season, in the Central Region is 3,235m3/ha and in the Central Highlands is
2,898m3/ha, the national average is 2,668m3/ha.
Water efficiency for electricity generation of hydropower plants in
17


Vietnam is determined to vary from 0.1334 to 1.4579 kWh per cubic meter. If

we calculate the average water efficiency for electricity generation in Vietnam
by dividing the total electricity generation by the total amount of water put
into the turbines of the six largest hydropower plants, the result is:
H=
= 0.1714 (kWh/m3)
It is noticeable that the water efficiency of the plants is not the same,
with one cubic meter of water generating this hydropower plant generating 10
times more electricity than other hydropower plants. The water efficiency of
the hydropower plant is directly proportional to the height of the water
column that is fed into the turbine. The equation for the efficiency of water
use (H) with the height of the water column (h) is written as follows.
H = 0.00298 × h0.93 + 0.00141, R2=0.97
3.2.2. Water retention per hectare of forest

- The value of water retention per hectare of forest in different basins is
relatively clear. The aggregate value of water retention per hectare of forest
from 530,000 to 1,500,000 VND depending on the basin characteristics and
water efficiency of a hydropower plant.
The close relationship of the environmental service value of a hectare of
forest with the influencing factors is shown in the empirical equation with a
high correlation coefficient. E = -221445-7806,74 × (TLRQD2)+2093,954 ×
(Hcn) +22022 × Doc + 529,36 × (mua), R=0,95
3.2.3. Water retention of forest per kWh of electricity

- The average water retention value of the forest per kWh of electricity
also depends on many factors, especially the height of the water column to the
turbine of the plant, ranging from 63 to 368 VND / kWh, an average of 214
VND / kWh. electricity.
- The related equation for the value of forest environmental protection
services in forests per kWh is: E = 266,91709 + 2,94894 × (TLRQD2) 0,56876 × (Hcn) - 11,19798 × Doc - 0,00246 × (mua), R=0,72

3.2.4. Water retention of forest per cubic meter of water

The average water retention value of forest per cubic meter of water
depends primarily on the height of the water column to the turbine of the
plant and less on other factors.
The equation for efficiency of water use (H) with the height of water
column (h) is written as follows:
H = 0,00298 ×
+ 0,00141; R² = 0,97
The PFES value can be determined per cubic meter of water supplied by
the forest for hydropower plants in the dry season according to the following
equation:
Pm = 0.6528 × h + 7.79, R= 0.99
18


3.3. The monetary value of water retention efficiency of forests
3.3.1. Correction coefficient

3.3.1.1. Determine the correction coefficient
From the data on the characteristics related to the water retention
efficiency of forest, the dissertation has identified the correction coefficient K
according to the water retention efficiency (kW).
Calculation results show that, if the K correction coefficient for
protection forests is 1.0, the K coefficient for special use forests is 1.0 and
production forests is 0.9.
3.3.1.2. Proposal of the correction coefficient
Based on the analysis of the research results to determine the K
coefficient, the K coefficients can be given as follows:
K1 for a natural forest is 1.00 and planted forest is 0.80

K2 for a rich forest is 1.0; the medium forest is 0.95 and the poor forest
is 0.90
K3 for the protection forests is 1.00; the Special-use forest is 1.00 and
the Production forest is 0.9.
3.3.1.3. Correction coefficient for each forest plot in each specific case
For payment of forest environmental services in the areas of hydropower
reservoir for 1 forest plot, the final correction coefficient for the payment of
forest environmental services K for each forest plot in the cases of using 1, 2
or 3 criteria are as follows:
- When using the two criteria of forest origin and forest type, there will
be 4 combinations of forest characteristics to determine the K coefficient. The
combination of forest characteristics and the K coefficient after being rounded
to 0.05.
- When using the three criteria of forest origin, forest type, and forest
status, there will be 12 combinations of forest characteristics to determine the
K coefficient. The combination of forest characteristics and K coefficient
after being rounded to 0.05.
3.3.2. Range of water retention value of the forest

Based on the efficiency of water retention in the hydropower reservoirs,
the dissertation has determined the value of the water retention service of the
forest per kWh of electricity and per hectare of forest for 32 hydropower
plants with water collection area in 2 provinces or more.
Data show that the total water retention value per hectare of forest is
VND 211,490 and per 1 kWh of electricity is VND 47.
3.3.3. Range of water retention value per hectare of forest

The value of forest environmental services per hectare of forest varies
widely, depending on the characteristics of the basin and the water efficiency
19

of the plant. Based on the actual nationwide scope of fluctuations of the
criteria, this study has determined the range of forest environmental service
value per hectare in cases where the correction coefficient K is from 0.65 to
1.00; standard forest coverage rate is from 40 to 100%, rainfall is from 1,400
to 2,600mm, basin slope is from 10 to 260, height of water column into the
turbine from 20 to 200m.
3.3.4. Range of water retention value per kWh of electricity

The data show that the value of forest environmental services per kWh
of electricity ranges from about VND 35 to VND 400 / kWh.
3.3.5. Range of water retention value of forest per one cubic meter of water

The value of water retention service per cubic meter of water depends on
the water use efficiency of the hydropower plant. Using the empirical
equation relating to the value of water retention service of the forest with the
height of water column into the turbine, this study has built a table to look up
the water retention value of the forest.
3.4. Proposal the amount of payment for forest environmental services for
hydropower plants
3.4.1. Principles for determining the number of payments for forest
environmental services

This study has taken a number of principles to determine the number of
payments for forest environmental services as follows:
- The number of payments for forest environmental services must be
changed in accordance with the forest type, forest status, and forest formation
origin.
- The number of payments for forest environmental services must be

easily determined in practice.
- The number of payments for forest environmental services should
apply relatively uniformly, the amount of payment for forest environment
services to those with different technological levels, in places with different
favorable natural conditions.
- The number of payments for forest environmental services may not be
equal to the environmental value created by the forest.
- The amount of payments for forest environmental services depends on
the awareness and knowledge of stakeholders and the whole society.
3.4.2. The estimation of the range of payment for forest environmental services
for hydropower plants per kWh of electricity

Based on the amount of payment under the Decree No. 156 is VND36
per kWh of electricity and the advantages of payment options given for
consideration and proposal of a common amount of payment for hydropower
plants is VND 50 / kWh.
Thus, the amount of payment for forest environmental services in the
20


1kWh electricity selling price is: equivalent to 25% of the average value of
forest environmental services.
3.4.3. The estimation of payment for forest environmental services for hydroelectricity per hectare of forest

The study has defined a range of payment for environmental services per
hectare of forest with different K coefficients. It is expressed as (1) the
formula for determining the amount of payment for environmental services
for a hectare of standard forest, (2) the formula for determining the normative
forest area to pay for an environmental service of a hydropower plant, (3)
lookup table of payment amount, (4) the formula for determining amount of

payment, (5) lookup table of payment for forest plot with different K
coefficients.
(1)- the formula for determining the amount of payment Pc for
environmental services for a hectare of the standard forest:
Pc = I ×
Where:
Pc is the amount of payment for environmental services per hectare of
standard forest in the reservoir area.
I is the percentage of money used to pay directly for the forest plots after
deducting the money spent on fee management, contingency fund, etc. (about
0.85).
n1 is the number of hydropower plants that pay for FES for the forest area,
n2 is the number of water supply facilities that pay for FES for the forest
area,
Di is the commercial electricity output of ith hydropower plant,
Ni is the commercial water output of the ith water supply facility,
Sc1i is the standard forest area that the ith hydropower plant has to pay,
Sc2i is the standard forest area that the ith water supply facility has to pay
r is the payment for forest environmental services per 1 kWh of electricity,
40 is the rate of payment for forest environmental services per cubic meter
of water supplied by a water supply facility.
(2)- The formula for determining the standard forest area
Sc =
Where:
Sc is the standard forest area that the hydropower plant has to pay for
forest environmental services,
n is the number of forest plots in the catchment area (basin) of the
hydropower plant,
Si is the area of ith plot in the water collection area of the hydropower
plant,

21


K1i is the correction coefficient based on the forest origin of the ith
forest plot,
K2i is the correction coefficient based on the forest type of ith plot,
K3i is the correction coefficient based on the forest status of the ith
forest plot,
(3)- a lookup table of correction coefficients of payment for forest
environmental services of a forest plot
Correction coefficients K1, K2, and K3 of each forest plot are
determined according to their origin, status, and type of forest.
(4)- The formula for determining the amount of payment for
environmental services for a forest plot
Pli =Pc × Sci
Where:
Pli is the payment level for the ith forest plot,
Pc is the payment for environmental services for a standard hectare of
forest in the hydropower reservoir area,
Sci is the standard area of the ith forest plot,
Sci = Si × K1 × K2 × K3,
Si is the area of the ith forest plot,
(5) A lookup table of payment for environmental services for one hectare
of the forest plot with different K coefficients
Based on the principle of calculating the amount of payment for forest
environmental services based on the correction coefficient K and the
fluctuation scope of the payment amount of forest environmental services, the
study has built a table of payment amount for environmental services per
hectare of a forest plot with different K coefficients.

22


CHAPTER 4. CONCLUSIONS

4.1. Conclusions
1. Within the scope of this study, dry season flow volume is an important
indicator of the role of forest water retention in hydropower reservoirs. It
increases with the proportion of forest cover, rainfall and average slope of the
basin. The water retention efficiency of each hectare of forest ranges from
1,839 to 4,565 m3 / ha. In the North, an average of 1 ha of forest holds 3,162
m3 / ha of water to provide hydroelectricity in the dry season, in the Central
Region is 3,235 m3 / ha and in the Central Highlands is 2,898 m3 / ha, the
national average is 2,668 m3 / ha.
2. In the study areas, the total water retention value of a standard hectare
of forest in the Northern basin is VND 860,272, the Central is VND 975,241
VND, and the Central Highlands is VND 765,638 VND. The total average
water retention value per kWh of electricity in the North is 162 VND / kWh,
in the Central is 171 VND / kWh, in the Central Highlands is 223 VND /
kWh. On a national average, the water retention value per hectare of forest is
836,970 VND and per 1 kWh of electricity is 199 VND.
3. The correction coefficient for the payment of environmental services
for the forest plot in the hydropower reservoir is determined by comparing
indicators reflecting the water retention value of forest types, forest status and
forest origin. K1 for the natural forest is 1.00 and the plantation is 0.80, K2
for the rich forest is 1.0, the medium forest is 0.95 and the poor forest is 0.90,
K3 is for protection forest is 1.00, the special-use forest is 1.00, and the
production forest is 0.9.
4. Within the study basins, the water retention value per hectare of forest
in the study basins ranges from 530,000 to 1,500,000 VND. The water

retention value of the forest per kWh of electricity ranges from 63 to 368
VND, the average value is 203 VND / kWh. The average water retention
value of the forest per cubic meter of water in the North is 67 VND / m3, in
the Central is 124 VND / m3 and in the Central Highlands is 58 VND / m3.
5. In the whole country, the amount of payment for forest environmental
services per hectare of forest (P) ranges from 50,000 VND to 1,700,000 VND
/ ha of forest, calculated for one kWh of electricity ranging from 35 VND to
400 VND / kWh, calculated per cubic meter of water, ranging from 20 to 350
VND / m3,
6. The range of payment for forest environmental services includes: (1) the proposed amount of payment for the hydroelectric plant is VND 50 / kWh,
which is equal to 25% of the increased revenue due to forest environmental
services, equal to 4% of current electricity price, (2) amount of payment per
hectare of forest ranges from VND 1,084 / ha of forest to VND 1,701,852 / ha
23


of forest, the average amount is VND 897,047 / ha of forest.
4.2. Existence and recommendations
The study is not eligible for actualizing the amount of payment for forest
environmental services. Recommend the management agencies of the
payment for forest environmental services to create conditions for applying
the study results to the reality of payment for forest environmental services.
This study has not yet studied the K coefficient related to the difficulty
level in forest protection and management. Further studies need to be
additionally studied for the K coefficient according to these difficult
conditions.

24