1.2 Detalles de contacto de las personas de referencia e instituciones involucradas en la evaluación y la documentación de la Tecnología

Nombre de la(s) institución(es) que facilitaron la documentación/ evaluación de la Tecnología (si fuera relevante)

Technische Hochschule Köln (TH Köln) - Alemania

1.3 Condiciones referidas al uso de datos documentados mediante WOCAT

¿Cuándo se compilaron los datos (en el campo)?

03/08/2015

El compilador y la/s persona(s) de referencia claves aceptan las condiciones acerca del uso de los datos documentados mediante WOCAT:

Sí

1.4 Declaración de la sostenibilidad de la Tecnología descrita

¿La Tecnología aquí descrita resulta problemática en relación a la degradación de la tierra, de tal forma que no puede considerársela una tecnología sostenible para el manejo de la tierra?

No

2.1 Breve descripción de la Tecnología

Definición de la Tecnología:

Return flow from paddy fields is strategically collected before being lost to rivers and is reused as an effective source of agricultural water.

2.2 Descripción detallada de la Tecnología

Descripción:

Return flow from paddy fields is defined as applied water that is not lost by evapotranspiration but returns to an aquifer or surface water body (Womach, 2005). The two types of return flow are surface and sub-surface. Surface return flow accounts for the major proportion. If surface return flow is strategically collected before entering rivers, it can be used as an ‘extra’ effective source of agricultural water supply (Phil King, 2008; Simons et al., 2015). Because paddies effectively purify water by absorbing nitrogen and phosphorus, this produces return flow of an acceptable quality for irrigation purposes. Return flow can be collected by drainage canals and stored in ponds and reservoirs, and then returned to pumps for reapplication. This technology offers one solution towards overcoming a deficit of irrigation water.

The goal of this technology is to store and reuse surface return flow from paddy farms to enhance irrigation efficiency. The purpose of constructing temporary barriers in drainage canals is to minimise water wastage and optimise the possibility of collecting and recycling surface return flow. Return flow from irrigation system is stored in surrounding ponds and reservoirs Return flow can only be used when it is captured in a storage structure or drain which has a hydraulic link to the irrigation source: thus an integrated framework for the reuse system consisting of both hydraulic, and management, links should be established. Within the scope of this study, the Water Management Unit (WMU) is understood as an integrated irrigation and drainage system consisting of four components: (i) the hydrological catchment which covers both non-irrigated and irrigated area; (ii) the source scheme generating return flow; (iii) the reuse scheme that is hydraulically connected with the source scheme; and (iv) a drainage system functioning as a harvesting as well as a supply structure.

Before implementing such a system it is recommended to analyse the correlation between irrigation efficiency and reuse of return flow, as well as developing a framework for managing and recycling return flow. Investigation aims at identifying the potential of return flow for irrigation; determining its quantity and quality; and developing an efficient and sustainable reuse framework. Water balance calculations, field measurements, water quality sampling and interviewing are all used for this purpose.

In the study area, long dry seasons cause severe water shortages and problems with saline intrusion. The study area is mainly covered by paddy, vegetables and other annual crops such as maize, sweet potatoes, peanuts and sugarcane. Paddy rice, which consumes a high proportion of the freshwater, is the dominant crop. Agricultural land in the downstream area is irrigated through gravity or pump irrigation systems. Here results indicate that the irrigation efficiency can be improved significantly: the irrigation efficiency of Tu Cau and Thanh Quyt irrigation schemes is projected to increase respectively by 1.8 and 1.4 times.

Reuse of return flow can be applied in all WMUs where the drainage canals are connected with storage tanks. Scientific and technical support tools are offered by the Vu Gia Thu Bon River Basin Information Centre. The centre was established in Danang providing a comprehensive information service to farmers and other water users – it includes capacity building and consulting services also.

2.3 Fotografías de la Tecnología

2.5 País/ región/ lugares donde la Tecnología fue aplicada y que se hallan comprendidos por esta evaluación

2.6 Fecha de la implementación

Si no se conoce el año preciso, indique la fecha aproximada:

• hace menos de 10 años (recientemente)

2.7 Introducción de la Tecnología

Especifique cómo se introdujo la Tecnología:

• mediante la innovación de usuarios de tierras
• durante experimentos/ investigación

3.1 Propósito(s) principal(es) de la Tecnología MST

• mejorar la producción
• conservar el ecosistema

3.2 Tipo(s) actuales de uso de la tierra donde se aplica la Tecnología

Comentarios:

Major land use problems (compiler’s opinion): The lowland part of Vu Gia Thu Bon is an intensive agricultural area. Rice cultivation, which consumes a high proportion of fresh water, accounts for 70% of total agricultural land (Ribbe et al., 2011). Since 2005, due to the impacts of droughts and saltwater intrusion, water for irrigation during the dry seasons has become an increasing problem in the lowland area of this basin. Simultaneously, the irrigation efficiency of this region is relative low. Various measures are applied to address water scarcity for irrigation. Reusing return flow is regarded as a potentially new measure to reduce the severity of the irrigation deficit in dry periods.
Major land use problems (land users’ perception): Based on the information provided by the Department of Natural Resources and Environment (DONRE) for Quang Nam Province, this basin now faces the problem of temporarily insufficient irrigation water. This situation is caused by droughts, insufficient reservoir capacity, salinity intrusion and ineffective irrigation management.

3.3 Información adicional sobre el uso de tierras

Provisión de agua para la tierra donde se aplica la Tecnología:

• totalmente irrigada

Número de temporadas de cultivo por año:

• 2

Especifique:

Longest growing period in days: 130, Longest growing period from month to month: 20th December to 28th April; Second longest growing period in days: 110, Second longest growing period from month to month: 20th May to 06th September

3.4 Grupo MST al que pertenece la Tecnología

• cosecha de agua
• manejo de agua superficial (manantial, río, lagos, mar):

3.5 Difusión de la Tecnología

Comentarios:

Total area covered by the SLM Technology is 0.916 m2.
The research area is located in the downstream of the Vu Gia Thu Bon Basin (VGTB), Central Coast of Vietnam. Based on the hydraulic connectivity, the lowland of the VGTB is divided into 13 Water Management Units (WMU) (Viet, 2014). Of which, the Dong Quang and Tu Cau WMUs are selected to conduct the field survey and water quality sampling.

3.6 Medidas MST que componen la Tecnología

3.7 Principales tipos de degradación del suelo encarados con la Tecnología

Comentarios:

Main causes of degradation: crop management (annual, perennial, tree/shrub) (Paddy rice requires huge amounts of water. Meanwhile, the coefficient of irrigation return flow from paddy field is also quite high.), industrial activities and mining (Hydropower construction reduces water availability for irrigation), over abstraction / excessive withdrawal of water (for irrigation, industry, etc.) (It causes water waste and reduces irrigation efficiency.), change of seasonal rainfall (It affects the paddy water balance and actual irrigation need.), droughts (It causes saltwater intrusion.)
Secondary causes of degradation: change in temperature (It relates to evapotranspiration.), inputs and infrastructure: (roads, markets, distribution of water points, other, …), governance / institutional

3.8 Prevención, reducción o restauración de la degradación del suelo

Especifique la meta de la Tecnología con relación a la degradación de la tierra:

• reducir la degradación del suelo

4.1 Dibujo técnico de la Tecnología

4.2 Especificaciones técnicas/ explicaciones del dibujo técnico

Methods of recycling return flow from paddy fields: The surface return flow can be captured by drainage canals and stored in tanks: return water from these reservoirs is pumped back into irrigation canals.
In 2012, the first on-farm irrigation structure was initially implemented in the Tu Cau WMU in order to use return flow for irrigation purposes. The existing Sen Pond was enlarged and a temporary pumping station was installed to pump water into the irrigation canal system.
According to the pumping diary of Tu Cau station (in Winter-Spring crop 2013), there were totally 7 irrigation periods (8-11 days/period). Total input water (including effective rainfall) during the measuring period from 01 March to 10 April was about 28,000 m3. Meanwhile the total volume of return flow of the Tu Cau site was 16,176 m3. This amount of return flow has the potential to irrigate the agricultural area for about 16 days, equivalent to one and a half irrigation periods. The overall efficiency of the irrigation system will be significantly improved.
Location: Lowland area of VGTB Basin. Quang Nam Province
Date: January 2014

Technical knowledge required for field staff / advisors: high
Technical knowledge required for land users: low
Main technical functions: water harvesting / increase water supply

Dam/ pan/ pond
Depth of ditches/pits/dams (m): 2
Width of ditches/pits/dams (m): 194.9
Length of ditches/pits/dams (m): 399.4

Wall/ barrier
Height of bunds/banks/others (m): 0.5
Width of bunds/banks/others (m): 0.25
Length of bunds/banks/others (m): 1.26

Construction material (other): Stone, sandy bags and bamboo sticks
Specification of dams/ pans/ ponds: Capacity 116764.59m3
Catchment area: 77860 m²m2
Beneficial area: 30 ham2
Other type of management: Return flow is the part of drainage flow, it is necessary to enhance the institutional link to develop the reuse framework for the study area. Think about reforming IMC to IDMC with D is drainage.

4.3 Información general sobre el cálculo de insumos y costos

otra / moneda nacional (especifique):

VND

Indique la tasa de cambio de USD a la moneda local (si fuese relevante): 1 USD =:

20828,0

4.4 Actividades de establecimiento

	Actividad	Tipo de medida	Momento
1.	Building temporary barrier in drainage canal	Estructurales
2.	Dredging and expanding Sen Pond	Estructurales	12 months
3.	Installing and operating the temporary pump at Sen Pond, P is 15KW (Q=520-600m3/h)	Estructurales

4.5 Costos e insumos necesarios para el establecimiento

	Especifique insumo	Unidad	Cantidad	Costos por unidad	Costos totales por insumo	% de los costos cubiertos por los usuarios de las tierras
Mano de obra	labour		1,0	3046,52	3046,52
Equipo	machine use		1,0	5344,09	5344,09
Equipo	hammer, iron wire		1,0	2,4	2,4	100,0
Material de construcción	Stone,sandy bags,bamboo sticks		1,0	6,45	6,45	100,0
Material de construcción	Earth, concrete		1,0	1335,8	1335,8
Costos totales para establecer la Tecnología					9735,26

Comentarios:

Duration of establishment phase: 12 month(s)

4.6 Actividades de establecimiento/ recurrentes

	Actividad	Tipo de medida	Momento/ frequencia
1.	Temporary barrier	Estructurales	each cropping season
2.	Temporary pump	Estructurales	annually

4.7 Costos e insumos necesarios para actividades de mantenimiento/ recurrentes (por año)

	Especifique insumo	Unidad	Cantidad	Costos por unidad	Costos totales por insumo	% de los costos cubiertos por los usuarios de las tierras
Mano de obra	labour		1,0	24,0	24,0	30,0
Equipo	machine use		1,0	38,41	38,41
Material de construcción	Stone,sandy bags,bamboo sticks		1,0	3,22	3,22	100,0
Indique los costos totales para mantenecer la Tecnología					65,63

4.8 Factores más determinantes que afectan los costos:

Describa los factores más determinantes que afectan los costos:

Prices of the material and equipment; the approval procedure and disbursement process of the project of “Dredging and expanding Sen Pond”; the compensation cost for the farmers; the cost of operating and maintaining temporary pump; the cost of reinforcing the drainage canals.

5.1 Clima

5.2 Topografía

5.3 Suelos

5.4 Disponibilidad y calidad de agua

5.5 Biodiversidad

5.6 Las características de los usuarios de la tierra que aplican la Tecnología

Indique otras características relevantes de los usuarios de las tierras:

Land users applying the Technology are mainly common / average land users
Population density: > 500 persons/km2
Annual population growth: 1% - 2%
1% of the land users are very rich and own 3% of the land.
2% of the land users are rich and own 7% of the land.
70% of the land users are average wealthy and own 60% of the land.
25% of the land users are poor and own 20% of the land.
2% of the land users are poor and own 10% of the land.
Off-farm income specification: There is a large industrial park located near the study site and a large part of the working population in the region is earning income by working in the factories.

5.7 Área promedio de la tierra que pertenece a o es arrendada por usuarios de tierra que aplican la Tecnología

5.8 Tenencia de tierra, uso de tierra y derechos de uso de agua

Tenencia de tierra:

• estado

• farmer, individual

Derechos de uso de agua:

• acceso abierto (no organizado)

• farmer, individual

5.9 Acceso a servicios e infraestructura

6.1 Impactos in situ demostrados por la Tecnología

Impactos socioeconómicos

Producción

Disponibilidad y calidad de agua

Otros impactos socioeconómicos

Impactos socioculturales

Impactos ecológicos

Ciclo de agua/ escurrimiento de sedimento

Suelo

Otros impactos ecológicos

6.3 Exposición y sensibilidad de la Tecnología al cambio climático gradual y a extremos relacionados al clima/ desastres (desde la percepción de los usuarios de tierras)

Cambio climático gradual

Cambio climático gradual

	Estación	tipo de cambios climáticos/ climas extremos	¿Cómo es que la tecnología soporta esto?
temperatura anual		incrementó	no muy bien

Extremos (desastres) relacionados al clima

Desastres climatológicos:

	¿Cómo es que la tecnología soporta esto?
tormenta de lluvia local	bien
tormenta de viento	no se sabe

Desastres climatológicos

	¿Cómo es que la tecnología soporta esto?
sequía	bien

Desastres hidrológicos

	¿Cómo es que la tecnología soporta esto?
inundación general (río)	no se sabe

Otras consecuencias relacionadas al clima

Otras consecuencias relacionadas al clima

	¿Cómo es que la tecnología soporta esto?
periodo reducido de crecimiento	no muy bien

6.4 Análisis costo-beneficio

¿Cómo se comparan los beneficios con los costos de establecimiento (desde la perspectiva de los usuarios de tierra)?

¿Cómo se comparan los beneficios con los costos de mantenimiento/ recurrentes (desde la perspectiva de los usuarios de tierra)?

6.5 Adopción de la Tecnología

De todos quienes adoptaron la Tecnología, ¿cuántos lo hicieron espontáneamente, es decir, sin recibir incentivos/ pagos materiales?

• 50-90%

Comentarios:

By applying the technology, the potential reuse area of return flow is estimated about 33% of the study area (30.4ha of agricultural area is potentially irrigated by return flow). However, estimating the number of land user families that have implemented the technology is not the initial aim of the study. Therefore, it requires further detailed investigation and social survey as well.

6.7 Fuerzas/ ventajas/ oportunidades de la Tecnología

Fuerzas/ ventajas/ oportunidades desde la perspectiva del usuario de la tierra
Increases the water depth in paddy fields which helps to improve paddy productivity
Beneficial/ endangered species might obtain new habitats in the retention area

Fuerzas/ ventajas/ oportunidades desde la perspectiva del compilador o de otra persona de referencia clave
Using return flow is helpful to improve irrigation efficiency. The amount of extracting water for irrigation and the cost of operating an irrigation system can be reduced.
The measure contributes to mitigating negative impacts of drought and salt intrusion. During the dry season the river water becomes more and more saline due to salt water intrusion. Salinity also builds up from not leaching out salts in the subsoil
Take advantages of available drainage canals, ponds, reservoirs to reduce the investment costs
Acceptable water quality because of the purification function of paddies which removes nutrients from the water
Low costs of conveyance systems because of short distance. More flexibility of allocation because of stable return flow. Less conflict between sectors.

6.8 Debilidades/ desventajas/ riesgos de la Tecnología y formas de sobreponerse a ellos

Debilidades/ desventajas/ riesgos desde la perspectiva del compilador o de otra persona de referencia clave	¿Cómo sobreponerse a ellas?
Temporal and spatial variation causes difficulty in using return flow. The differences in soil type, terrain, storage capacity of the paddy fields and irrigation method (e.g. irrigation techniques, the amount of input water and pumping intervals) are major factors influencing the quantity of return flow	Constructing temporary barriers in the drainage canal helps to minimise the water wastage and optimise the possibility of collecting and recycling surface return flow.
Using return flow might spread diseases, and weed seeds from affected farms to safe farms	Encourage farmers to comply with the principles of prevention and control diseases in agricultural production. It is necessary to implement preliminary tests and analyses the quality of return water before recycling for irrigation purposes.

7.1 Métodos/ fuentes de información

7.2 Vínculos a las publicaciones disponibles

Título, autor, año, ISBN:

Kim, H. K. et al. (2009) Estimation of irrigation return flow from paddy fields considering the soil moisture

¿Dónde se halla disponible? ¿Costo?

Agricultural Water Management, 96(5), 875–882.

Título, autor, año, ISBN:

Phil King (2008) Return Flow Efficiency

¿Dónde se halla disponible? ¿Costo?

New Mexico Water Resources Research Institute

Título, autor, año, ISBN:

Simons, G.W.H. et al. (2015) Water reuse in river basins with multiple users: A literature review

¿Dónde se halla disponible? ¿Costo?

Journal of Hydrology. 558–571

Título, autor, año, ISBN:

Ribbe et al. (2011) Annex 2 to Milestone Report 2011 - Description of the Study Region including an updated stakeholder analysis,

¿Dónde se halla disponible? ¿Costo?

LUCCi project. ITT, Cologne University of Applied Sciences