1.2 Contact details of resource persons and institutions involved in the assessment and documentation of the Technology

Name of project which facilitated the documentation/ evaluation of the Technology (if relevant)

Name of the institution(s) which facilitated the documentation/ evaluation of the Technology (if relevant)

1.3 Conditions regarding the use of data documented through WOCAT

The compiler and key resource person(s) accept the conditions regarding the use of data documented through WOCAT:

Yes

1.4 Declaration on sustainability of the described Technology

Is the Technology described here problematic with regard to land degradation, so that it cannot be declared a sustainable land management technology?

No

1.5 Reference to Questionnaire(s) on SLM Approaches (documented using WOCAT)

Climate-Smart Village Approach [Bhutan]

Climate change has become inevitable, and there is a need to address this impending danger. In the Climate-Smart Village (CSV) approach, land users in Ngaru-Pongtang have implemented several technologies and innovations to address climate change impacts, and the programme has worked with 50 households on a total area of 137 …

• Compiler: ONGPO LEPCHA
• 07/13/2023 1:58 p.m.

2.1 Short description of the Technology

Definition of the Technology:

Low-cost plastic-lined water harvesting ponds collect and store rain and overland flow water for agricultural and domestic purposes in the dry season. They are both economic and efficient.

2.2 Detailed description of the Technology

Description:

Low-cost plastic-lined water harvesting pond are used to collect and store rain or overland flow water for agricultural purposes in the dry season. They are economic and efficient. These ponds are required in the context of irrigation water shortages. Although rainfall has been projected to be increasing (NCHM, 2017), irrigation water shortage was - and continues to be - one of the major constraints in crop production (IHPP, 2017).
Water from precipitation and surface water sources is lost due to inadequate collection and storage. Villages at the top of the hills, in particular, suffer from acute irrigation as well as drinking water shortages. To tap and collect wastewater, rainwater, and water from other perennial and non-perennial sources, low-cost plastic lined water harvesting ponds are proposed. This water can be used during the dry or “lean” season for agricultural as well as household purposes.
The proposed model pond (plastic sheet size; 9m * 7m) costs less than Nu. 25, 000 (USD 315) for construction but can hold more than 27, 000 litre of water. The same dimension of pond if constructed using concrete, would cost more than Nu. 1, 19, 000 (USD 1500). Furthermore a 10, 000 litre synthetic tank available on the market costs more than Nu.35, 000.
Irrigation water shortage results in fallow lands. It is reported that 6,400 acres (2,600 ha) of irrigable land was left fallow in 2016 and 26 % of the total households surveyed were affected by irrigation water shortages (DoA, 2016). By reducing fallow land and increasing crop production, this technology could be a stepping stone towards food self-sufficiency – as well as providing water for consumption by people and livestock.
Though a similar technology is said to have introduced in the country many years ago, the present form of the technology was introduced to Barshong gewog in Tsirang Dzongkhag by the ‘Himalica’ pilot project in 2014. However, the proposed technology has been modified and improved to suit to the topography and needs of farmers in Bhutan. The proposed pond design is a reverse truncated square pyramid shape unlike the cuboid shape ponds of ICIMOD’s. The pond is designed in such way as to increase pond stability and ease of construction.
Concrete tanks require specific construction methods and faults can develop with ice freezing and expanding in cracks in tank walls during the winter (Slater, 2011). Plastic (silpaulin) sheet lined ponds are leak-proof and primarily depend on the longevity of the plastic sheet unlike concrete tanks. Concrete water tanks, (especially elevated tanks) are also prone to damage due seismic activities (Housner, 1963).
The low-cost plastic lined water harvesting pond adopted is cheap, environmentally friendly, and has positive social impacts. It reduces irrigation water constraints, addresses fallow land problems, and supplements water for domestic purposes. The technology is a tool for reducing poverty, expanding cultivated land and increasing food self-sufficiency resulting in a healthier and happier society.

2.3 Photos of the Technology

2.5 Country/ region/ locations where the Technology has been applied and which are covered by this assessment

Country:

Bhutan

Region/ State/ Province:

Dagana Dzongkhag

Further specification of location:

Pangserpo Chiwog, Drujeygang Gewog

Specify the spread of the Technology:

• applied at specific points/ concentrated on a small area

Is/are the technology site(s) located in a permanently protected area?

No

Comments:

The technology is located in the land users field.

Map

×

2.6 Date of implementation

Indicate year of implementation:

2019

2.7 Introduction of the Technology

Specify how the Technology was introduced:

• through projects/ external interventions

Comments (type of project, etc.):

The technology was initiated by Agriculture Research and Development Centre Bajo through fund support of Food Security and Agriculture Productivity Project of the World Bank. Drujegang, Kana and three blocks of Lhamoidzingkha sub-district of Dagana districts were selected as the project sites.

3.1 Main purpose(s) of the Technology

• improve production
• reduce, prevent, restore land degradation
• adapt to climate change/ extremes and its impacts
• create beneficial economic impact
• create beneficial social impact

3.2 Current land use type(s) where the Technology is applied

Land use mixed within the same land unit:

Yes

Specify mixed land use (crops/ grazing/ trees):

• Agroforestry

Cropland

• Annual cropping
• Tree and shrub cropping

Annual cropping - Specify crops:

• legumes and pulses - beans
• root/tuber crops - potatoes
• vegetables - leafy vegetables (salads, cabbage, spinach, other)
• vegetables - other
• vegetables - root vegetables (carrots, onions, beet, other)

• chilli, onion

Tree and shrub cropping - Specify crops:

• citrus

Number of growing seasons per year:

• 2

Is intercropping practiced?

Yes

If yes, specify which crops are intercropped:

Vegetables intercropped within citrus orchard

Is crop rotation practiced?

Yes

If yes, specify:

The land users grow different crops in the same area. For example, if they plant potatoes this year, they plant beans next year.

3.3 Has land use changed due to the implementation of the Technology?

Has land use changed due to the implementation of the Technology?

• No (Continue with question 3.4)

3.4 Water supply

Water supply for the land on which the Technology is applied:

• mixed rainfed-irrigated

3.5 SLM group to which the Technology belongs

• water harvesting
• irrigation management (incl. water supply, drainage)

3.6 SLM measures comprising the Technology

structural measures

• S5: Dams, pans, ponds
• S7: Water harvesting/ supply/ irrigation equipment

3.7 Main types of land degradation addressed by the Technology

soil erosion by water

• Wt: loss of topsoil/ surface erosion

water degradation

• Hs: change in quantity of surface water

3.8 Prevention, reduction, or restoration of land degradation

Specify the goal of the Technology with regard to land degradation:

• reduce land degradation
• restore/ rehabilitate severely degraded land

4.1 Technical drawing of the Technology

Technical specifications (related to technical drawing):

Site selection for pond construction:
Choose a site for the pond at the top of the farm for easy flow/use of water to the agricultural fields. Select the site only at the stable soils to avoid collapse, and bursting of the pond. Water sources for the pond may be perennial water sources, rainwater gutter systems, water from tap stand, and waste water from farm house or a combination of the different sources.
Materials required: The materials required for making the pond are:
1.Plastic sheet of desired length and breadth
a.250-300 GSM (gram per square meter)]
b.UV stabilized
2.Measuring tape (30m)
3.Shovel, spade, and crowbar
4.Mosquito net or similar ones
5.HDPE pipes, gates valves
6.Fencing materials (bamboo poles, wooden poles, barbed wire, nails, wire mesh, binding wire)
Procedure to dig the pond:
1.Clear the vegetation and level the ground to construct the harvesting pond.
2.Measure the base length (l), and the base breadth (b) on the leveled ground. These length and breadth will be the length and breadth of the pond floor. Dig out the soil till 1.2 m height (h) to construct a cuboidal pond.
3.From the top edges of the cuboidal pond, measure distance ‘g’ in all four sides. Make slanting cuts from the top to the base on all four sides. Scrap off soils on all sides to obtain slope of 700. The gradient is made for slope stabilization and convenience to lay out plastic sheet.
4.Make the cut surfaces including the floor smooth by using mud and cow dung paste or mud paste in order to avoid damages to the plastic sheet while laying out and when filled with water. The pit ready to lay out plastic sheets should have the dimensions.
5.Carefully lay out the plastic sheet over the pit. Keep an anchor length (overlap) of 0.5m on all sides of the pit. Fix wooden or bamboo pegs or iron rod through the eyelets of the plastic sheet and or cover the overlapping plastic edges by at least 10cm of mud or soil to strongly anchor the plastic sheet.
6.Construct a drain with 30cm width and 30cm depth around the edges of the plastic sheet which was covered with soil or mud. The drainage should slope towards a suitable drain out area.
7.Fence the pond using wire mesh/bamboo/wooden poles/timber to prevent mishaps or accidents. Fill the pond with water only after fencing. Galvanized wire mesh is preferable.
Using water:
Water from the pond can be used in the following ways:
Directly siphoning off with a pipe
Pumping up with a small motor pump
Taking out with suitable containers
Inserting a drain out pipe at one of the base corners.
The insertion of the drain out pipe should be done during the construction of the pond.

Note: The stone wall may be required in specific situations if built in a slope like this one but not generally needed. Technical drawing of the water harvesting pond without the cement structure is available at http://rcbajo.gov.bt/leaflet/ also shared under section 7 of this document.

Author:

Ongpo Lepcha

Date:

08/12/2023

4.2 General information regarding the calculation of inputs and costs

Specify how costs and inputs were calculated:

• per Technology unit

other/ national currency (specify):

Ngultrum (Nu.)

If relevant, indicate exchange rate from USD to local currency (e.g. 1 USD = 79.9 Brazilian Real): 1 USD =:

80.0

4.3 Establishment activities

4.4 Costs and inputs needed for establishment

If land user bore less than 100% of costs, indicate who covered the remaining costs:

The cost were for plastic sheet and wire mesh and were funded by Food Security and Agriculture Productivity project and Green Climate Fund project.

Comments:

Pit digging and laying of plastic sheets were all done manually by the land users. Bamboo used for fencing purposes was available locally. The labour cost was not borne by the land users as they implemented a system of labour-sharing where land users reciprocate by working for an equal number of days at other land users' households as compensation.

4.5 Maintenance/ recurrent activities

Comments:

Due to the unpredictable rainfall patterns and the associated risk of landslides as the pond is located on steep slopes, the farmer was required to reconstruct and reinforce the pond by utilizing cement to provide additional support. Ponds located in the plain or lower gradient do not require support using concrete walls.

4.6 Costs and inputs needed for maintenance/ recurrent activities (per year)

If land user bore less than 100% of costs, indicate who covered the remaining costs:

The cement was supported by the government.

Comments:

Boulders and stones used were collected from the land users' field.

4.7 Most important factors affecting the costs

Describe the most determinate factors affecting the costs:

The most important factors that affect the cost are the construction materials and labour. In this particular situation, cement wall is also one of the major factors affecting the cost although it is not usually required.

5.1 Climate

5.2 Topography

Indicate if the Technology is specifically applied in:

• convex situations

5.3 Soils

If available, attach full soil description or specify the available information, e.g. soil type, soil PH/ acidity, Cation Exchange Capacity, nitrogen, salinity etc.

Moisture content 3.38%, organic matter 4.19%, Organic carbon 2.44%, pH 6.31, electrical conductivity 93.30 µs/cm, nitrogen 0.12%, phosphorus 0.36 ppm, Potassium 301.07 mg/100ml, texture Loamy sand.
The soil analysis was conducted at the Science Laboratory of College of Natural Resources, Royal University of Bhutan, Lobesa, Punakha.

5.4 Water availability and quality

Is water salinity a problem?

No

Is flooding of the area occurring?

No

5.5 Biodiversity

5.6 Characteristics of land users applying the Technology

5.7 Average area of land used by land users applying the Technology

5.8 Land ownership, land use rights, and water use rights

Land ownership:

• individual, titled

Land use rights:

• individual

Water use rights:

• communal (organized)

Are land use rights based on a traditional legal system?

Yes

5.9 Access to services and infrastructure

6.1 On-site impacts the Technology has shown

Socio-economic impacts

Production

Water availability and quality

Income and costs

Socio-cultural impacts

Ecological impacts

Water cycle/ runoff

Biodiversity: vegetation, animals

Climate and disaster risk reduction

6.2 Off-site impacts the Technology has shown

6.3 Exposure and sensitivity of the Technology to gradual climate change and climate-related extremes/ disasters (as perceived by land users)

Gradual climate change

Gradual climate change

Comments:

The technology copes well with the decreasing rainfall as it captures the limited rainwater and makes it available for agricultural use.

6.4 Cost-benefit analysis

How do the benefits compare with the establishment costs (from land users’ perspective)?

How do the benefits compare with the maintenance/ recurrent costs (from land users' perspective)?

6.5 Adoption of the Technology

• 1-10%

Of all those who have adopted the Technology, how many did so spontaneously, i.e. without receiving any material incentives/ payments?

• 0-10%

Comments:

All the farmers who have adopted the technology were partially funded (external support).

6.6 Adaptation

Has the Technology been modified recently to adapt to changing conditions?

Yes

If yes, indicate to which changing conditions it was adapted:

• climatic change/ extremes

Specify adaptation of the Technology (design, material/ species, etc.):

The location of the water harvesting technology on slopes presents a risk of potential landslides caused due to climate change effects such as heavy rainfall. Therefore, the structure of the technology was modified to address this issue by providing support using the cemented wall. The modification is suitable for the steep slopes and is not required on the plain areas.

6.7 Strengths/ advantages/ opportunities of the Technology

6.8 Weaknesses/ disadvantages/ risks of the Technology and ways of overcoming them

7.1 Methods/ sources of information

7.3 Links to relevant online information

Title/ description:

Low cost plastic lined water harvesting pond

URL:

http://rcbajo.gov.bt/leaflet/