Effect of climate change on site suitability and reliability of small farm reservoir in Oriental Mindoro, Philippines

Issue Date

10-2019

Abstract

Despite of its abundance of water resources, the Philippines is confronted with issues pertinent to the availability and distribution of irrigation facilities. The use of GIS can revolutionize the method of identification and assessment of water resources and, therefore, maximize its utilization. The province of Oriental Mindoro, which is one of the major rice-producing provinces of the country, receives a total precipitation of 2,215 mm annually but the irrigation development remained slow at roughly 58% of the potential irrigable areas as of 2017. To combat the threats posed by drought, water conservation measures such as construction of rainwater harvesting structures for small farms, also known as small farm reservoirs (SFR), are widely adopted in the Philippines. In this study, a GIS-based framework was adopted in assessing the impact of climate change on suitability and reliability of SFR development in Oriental Mindoro. The suitability for SFR development was evaluated for a baseline period of 1970-2000 using annual rainfall, soil texture, and slope as factors. The weights applied to each factor were based on the criteria developed during the national consultation of researchers and experts on small-scale irrigation projects. The baseline and future climate data from an ensemble of six general circulation models (GCMs), namely CMCC-CM, IPSL-CM5A-LR, MIROC5, MPI-ESM-LR, MPI-ESM-MR, and MRI-CGCM3, under the Representative Concentration Pathways (RCP) 4.5 greenhouse gas emission scenario, were retrieved and downscaled using delta method to represent climatic conditions under a number of climate policy scenarios and strategies in 2050s (2041-2060) and 2070s (2061-2080). Reliability index (RI), which is defined as the ratio between the total storage capacity of SFRs and total crop water demand, was calculated for the same baseline period and future time horizons. The result of suitability analysis showed that 35.72%, 15.40%, and 47.56% of the total land area were classified as moderately suitable, highly suitable, and not suitable, respectively, during the baseline period. Field validation also showed that 87% of the existing SFRs sites were located in moderately suitable areas, and the remaining 13% were situated in highly suitable areas. Projected mean annual rainfall in the province decreased by 90 mm and 70 mm in 2050s and 2070s, respectively. However, these changes in annual rainfall have no significant effect on the spatial distribution and extent of suitable areas for SFR. Also, reliability analysis showed RI values of 2.90, 3.25, and 2.91 for baseline, 2050s, and 2070s respectively. These values indicate that the potential water supply from SFRs is more than enough to meet the crop water demand. This study suggests that GIS can be an effective tool in evaluating potential areas for SFRs and other small-scale irrigation projects as well as in planning for future irrigation development.

Source or Periodical Title

40th Asian Conference on Remote Sensing, ACRS 2019: "Progress of Remote Sensing Technology for Smart Future"

Page

1-10

Document Type

Conference Paper

Physical Description

illustrations; diagrams; graph; maps; tables; references

Language

English

Subject

Climate change, GIS, Suitability analysis

Digital Copy

yes

Link to Full Text

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