Applying Landsat-TM images to assess historical variations in the flood pulse of the Tonle Sap Great Lake system (Cambodia): importance for the dai fishery and species composition
Abstract
The Tonle Sap Great Lake (TSGL) system is the largest natural freshwater lake in SE Asia. Supporting more than 1.2 million people, the TSGL is vital for food security, livelihoods, flood regulation, and nutrient recycling. Its high fish diversity ( 200 described species) make the traditional dai fisheries (long-term monitored bag-net fishery) extremely productive and reliant on the hydrodynamics of the TSGL. During the wet season (May-October), the lake's flood area increases from 2,500 km2 to 18,000 km2. The flood pulse concept (FPC) has been used to explain the eco-hydrological interactions established between the permanent lake and the extensive floodplain-habitats, with the seasonality of the inundation pattern, triggering the migratory behaviour and growth of different fish guilds.
Yet, questions remain about the role of the FPC on the lake's historical inundation pattern and how variations in the flood regime reflect on the dai fishery and species yield. Additionally, future hydropower development and climate change scenarios in the Mekong River are expected to modify the flood regime, with the consequences for the dai fishery and reported species largely unknown. Here, we address these gaps in knowledge, by assessing the historical inundation pattern of the TSGL system and its influence on the dai catches and species composition. A 19-year (1996-2014) collection of Landsat-TM images and historical water level records from Kampong Luong (KL) gauging station permits the analysis of spatio-temporal variations in the lake's flood area. Relationships established between the flood regime, the dai catch and species composition reveal that increases in the duration and extension of the flood significantly influenced the catch yield (R2=0.37; p<0.05) and composition of large body-size medium and long distance migratory species (average body size: 50 cm; guilds 3 and 4; comprising 30% of the catch), which are highly impacted by anthropogenic modifications in the hydrologic regime. This study demonstrates the importance of preserving the historical flood pulse, for the seasonal inundation profile that drives the migratory behaviour and species composition of the dai catch, with guilds 3 and 4 likely to provide more than 50% of the averaged 70 kg person-1 year-1 of fish protein consumed by local populations.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMGC31K1382S
- Keywords:
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- 1622 Earth system modeling;
- GLOBAL CHANGEDE: 1630 Impacts of global change;
- GLOBAL CHANGEDE: 1632 Land cover change;
- GLOBAL CHANGEDE: 1640 Remote sensing;
- GLOBAL CHANGE