Water reservoirs

Development of water reservoirs for irrigation

According to projections, the Philippine climate will be wetter during wet seasons and drier during the dry seasons in 2020 and 2050. Thus, dependable flow for irrigation purposes may also vary, which will likely affect water supplies in major farm production areas.
Climate Adaptation Effectiveness

Surface runoff is sustained in all the scenarios with a relatively moderate decrease from 16 to 22% except for 2050 high-range scenarios. It had a large decline of about 82% relative to the baseline scenario. The lowest runoff in the 2050 high-range emission scenario amounting to 157.19 mm is equivalent to almost 9 million cubic meters of water collected from the 5067 hectares of catchment area. This only shows that reservoirs are a promising development project, which could serve as a source for supplemental irrigation during dry seasons. It will also be an important facility for flood mitigation. Moreover, it is being used as groundwater recharge in other countries. In addition, groundwater recharge is likely to increase even with increased GHG emissions. From the water balance results, percolation out of soil was the most contributing factor in the variability of groundwater recharge. Awan and Ismaeel (2014) found the same increasing trend in groundwater recharge and reported a 40% and 37% increase in representative concentration pathways (RCP) 4.5 and RCP 8.5, respectively. These RCP scenarios are also a representation of changes in rainfall and temperature because of GHG emissions. In the present study, the annual recharge of 310 mm by 2050 in high-range emissions is corresponding to an annual supply of 15.7 million cubic meters. Although recharge has an impact on groundwater levels, more importantly, groundwater extractions will affect the actual levels of groundwater in the area. Groundwater levels were not considered in the present study. (Alejo and Ella, 2019, pp.96-97).

Climate Hazards

  • Drought
  • Rainfall Variability

Locations

  • Victoria, Laguna, Region IV-A (CALABARZON)
  • Pila, Laguna, Region IV-A (CALABARZON)
  • Nagcarlan, Laguna, Region IV-A (CALABARZON)

Adaptation Sectors

  • Agriculture
  • Water Management

CCET Instuments

  • Research and Development

Target Group based on Vulnerability

Basic Sectors:
  • Farmers and Landless Rural Workers

Evaluations

Economic / Financial Effectiveness
No Evidence

It will entail expenses to conduct data gathering and field testing. However, once data is available. no maintainance costs were mentioned.

Technical Feasibility
Mid

In order to determine other potential sources for supplemental irrigation, technical knowledge and skills on Soil and Water Assessment Tool (SWAT) are needed. SWAT can run at the minimum available data set. The minimum data requirements for SWAT are weather, landuse, soil, and elevation...SWAT also uses DEM to draw the streams and flow accumulations. It is also the basis to calculate some watershed parameters such as sub-basin area, stream length, channel slope, and others. Many areas in the Philippines have limited to almost no hydrological information that is important for the proper assessment of irrigation sources thereby implicating difficulty in irrigation sustainability planning. To augment lack of data, many researchers published various methods for estimating these data with results acceptable to the scientific community. This study applied some of these techniques. (Alejo and Ella, 2019, p.89). The study does not have a long-term observed data that is essential for calibrating and validating SWAT. Data resources, however, are available in locations within 16 kilometers form the study site... Soil map from the Bureau of Soil and Water Management (BSWM) was considered in the study. It was validated on the ground using soil samples from rice paddies... Land use is a result of reclassied land cover map, which was sourced out from the National Mapping and Resource Information Authority (NAMRIA). (Alejo and Ella, 2019, p.89-90). Both calibration and validation of the Maasin River watershed using streamflow yielded a satisfactory result...These suggest that the model can adequately simulate streamflow of the river...These suggest that SWAT is applicable for streamflow simulations in Philippine watershed conditions. (Alejo and Ella, 2019, p.92).

Social Acceptability
No Evidence

No evidence of social acceptability

Environmental Impact
N/A

As a research-based initiative, implementing this climate change solution does not have direct environmental impacts.

Mitigation co-benefit

As a research-based initiative, there are no mitigative co-benefits applicable.

Keywords

supplemental irrigation, water reservoir, dry season, water supply

References

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