ASSESSMENT OF PAYMENT FOR ECOSYSTEM SERVICES IN SASUMUA CATCHMENT, KENYA

Abstract

The study was conducted in Sasumua watershed in Nyandarua County, Kenya. The catchment contains an important reservoir that supplies water to Nairobi. However, the intensive agriculture coupled with unsustainable agricultural practices including; deforestation, clearing of riparian buffers and intensive subdivision of land units leads to proliferation in soil erosion. This degrades water quality downstream leading to high maintenance cost of water infrastructure. The aim of the study was to assess the effectiveness of payment for ecosystem services (PES) approach as an alternative to watershed management. Baseline data on SLM adoption and water quality was collected before onset of PES pilot project. An assessment of PES was conducted one year into the project. Soil sampling was carried out to assess effectiveness of existing SLMPs specifically ‘fanya juu’ terraces on soil fertility and water holding properties. Total Suspended Solids (TSS) was selected as a proxy indicator to monitor water quality changes as SLM status improved under the PES project. Soil and Water Assessment Tool (SWAT) modelling was used to assist in interpretation of effectiveness of observed results against the best scenario of the study micro-catchment. The results showed that PES incentives (KES 4,541 per household), improved adoption of SLMPs from a baseline of 11% to 32% of the target SLM status after one year of PES implementation. Comparison of PES and non-PES farms showed significant differences in terms of SLM adoption. There was strong evidence that PES as an alternative approach led to positive changes towards SLMP adoption. On water quality, it was observed that Total Suspended Solids (TSS) significantly (p=0.00022) reduced from a baseline of 71.05mg/L to 42.73mg/L. The PES as an alternative was identified as an effective approach in improving water quality downstream. The PES incentives are expected to further improve soil and water conservation at farm level to ensure sustained delivery of the desired ecosystem services. However, long term research data is recommended to validate the effectiveness of PES over number of years especially on ecosystem services that manifest after long periods and establishing whether PES incentives actually maintain best conditions at farm level. More ecosystem services should also be monitored to validate the TSS results.