Estimating Sediment Export and Retention Capacity of Existing Land Cover in Balanac and Sta. Cruz Watersheds, Philippines Using InVEST-SDR Model

Abstract

Identifying priority areas for conservation remains a challenge since ecosystem-based models are typically data extensive. As a response to this challenge, InVEST (Integrated Valuation of Ecosystem Services and Tradeoffs) was developed to map diverse types of ecosystem services (ES). Although InVEST has been widely used in other countries, its application within the Philippines has been limited. This study offers an application of InVEST in the Philippine context. We estimated the amount of sediments exported to the streams and retained in the area by land cover type within the Balanac and Sta. Cruz watersheds. Results showed that in terms of best ecosystem service provision per hectare, vegetated areas – particularly forest land – provide the most sediment retention capacity and the least sediment export. On the other hand, the non-vegetated areas – particularly the built-up areas – provide the least sediment retention capacity and the most sediment export. These results suggest that major strategic water quality management and ES changes should be considered when converting land from one land cover type to another. Furthermore, a considerable opportunity for ecosystem service improvement to water quality through soil conservation and sustainable farming practices can be implemented in cropland areas. Since the majority of the land in both watersheds are cropland, its contribution in sediment transfers is significant, hence its role to managing soil health is of utmost importance. The findings of this study could contribute to the advancement of ES modeling in the Philippines to support land development planning and policy decisions at the national and local levels.

Drivers and impacts of land use and land cover changes on ecosystem services provided by the watersheds in the Philippines: a systematic literature review

“…(2013), and Ureta et al . (2022). It is important to note that one or more hydrologic parameters studied within the watershed may straddle between several ecosystem services.…”

“…2021, Graciela et al . 2018), and negative effects on water quality (Ureta et al . 2022) and nutrient levels (Dessie and Bredemeier 2013).…”

“…Few studies have also explored soil related functions of the watershed that is affected by LULC changes such as the study of Garcia (2016) in Makatipo Catchment, Lucban wherein soil loss was projected to increase in the future due to climate change and that land cover and slope characteristics influence soil erosion. Considering sediment retention, the forest cover was identified to provide the best retention capacity (Ureta et al 2022) as compared to other land uses. This finding was supported by the study of Almarines et al (2022), who mentioned that land cover remains an important predictor of sediment retention.…”

“…This category includes sub-categories such as decreased carbon stock, decreasing forest resources, degradation of water quality, lower nutrient concentration of water, and water quality reduction. These impacts underscore the significant changes in environmental conditions resulting from LULC change, including the loss of carbon storage , depletion of forest resources (Briones et al 2016, Graciela et al 2018, and negative effects on water quality (Ureta et al 2022) and nutrient levels (Dessie and Bredemeier 2013).…”

“…In the study conducted by Engay-Gutierrez (2015), investments on land resulted in more job opportunities, however, the continuity of this socio-economic development was still threatened due to undesirable consequences of altering the land cover such as sedimentation and flooding. With this, initiatives such as land use planning, land conversion regulation (Palao et al 2013), and up to date management planning (Carl Ureta et al 2022, Estoque et al 2018) are recommended. Also, Bato et al (2021) emphasized the importance of reforestation in areas susceptible to soil erosion, while Garcia (2016) stressed the formulation of adaptation measures which included increasing local resilience to combat the effects of soil erosion and the importance of strict implementation of policies geared towards improving the overall health of the watersheds.…”