Quantification of an overlooked water resource in the tropical rainfed lowlands using RapidEye satellite data: A case of farm ponds and the potential gross value for smallholder production in southern Laos
2019
Vote, Camilla | Eberbach, Philip | Inthavong, Thavone | Lampayan, Rubenito M. | Vongthilard, Somsamay | Wade, Len J.
In southern Laos, water stored in farm ponds is largely underutilised as it is perceived to be unfit for human consumption; subsequently, groundwater is the preferred source for domestic and agricultural consumption. For the first time, this paper presents the results of a study designed to quantify the total pond water volume within the landscape via remote-sensing methods in two districts in Champasak province that could be used to improve rural household cash income through the expansion of market-oriented dry season crop production. Water bodies were delineated via simple classification of RapidEye data using the Normalised Difference Water Index and a sub-classification was performed to distinguish between ponds and the streamflow network. Final estimates of total pond volume in Sukhuma and Phonthong districts were ∼2.30 × 10⁶ m³ and 3.55 × 10⁶ m³, respectively; and the average pond volume across both districts was ∼1987 m³. Sensitivity analysis of the potential gross value of farm ponds for irrigation of dry season, vegetable production typical of market-oriented smallholder activities in the area indicated that substantial gross economic gains could be made from better use and management of these resources.
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