Community-based stream and groundwater monitoring and future change impact modelling of a socio-ecohydrological system to inform drought adaptation in the seasonally-dry tropics

Changing Water Resources Under El Niño, Climate Change, and Growing Water Demands in Seasonally Dry Tropical Watersheds

“…Dominant land use in the two watersheds is forest (52%), pasture (38%), agriculture (8%), as well as residential (2%) based on a 2010 land use classification by Garcia-Serrano (2015) (Figure 1a). A review of satellite imagery reveals that minor land use change has occurred since then (Hund, 2018). Most agricultural fields are double cropped, with rainfed upland nonpaddy rice during the wet season, and groundwater-irrigated melons during the dry season, although some fields are planted with rice during the wet season and lie fallow in the dry season (Morillas et al, 2019).…”

“…We first assumed a business-as-usual water demand per person (i.e., water demand based on historical data) and then also explored potential sociohydrological responses of humans to a drier climate. Research has shown that domestic water demand is typically higher during the dry season in these watersheds (Hund, 2018). Thus, there might be the potential for increased domestic water use in a drier climate.…”

“…To explore these two possibilities of increased/decreased water demand, we analyzed two scenarios, in which we considered an increase/decrease of 18% in annual per person water demand for two of the climate change scenarios (GCM6 and reduced early rainfall scenario). The ±18% change was based on detailed analysis of changing water demands between wet and dry seasons (Hund, 2018).…”

“…The focus of these scenarios was on changes in climate and domestic water demand. Recent land use change within the Potrero and Caimital watersheds has been minimal, affecting less than 4% of total area from 2005 to 2016 watersheds (Hund, 2018). Therefore, we did not include any land use change scenarios in this analysis while acknowledging that land use and land cover changes can substantially impact ET and rainfall-runoff processes and could be explored in future research.…”

“…With the majority of the intense rainfall contributing to typically short-duration stormflow events (Hund, 2018), groundwater recharge constitutes a relatively small percentage of total annual rainfall. This is likely due to a combination of high rainfall intensity, relatively low infiltration capacity of the silty clay and loam soil in the alluvial valley, and the shallowness of the aquifer where groundwater levels often approach the soil surface toward the end of the wet season (Hund, 2018).…”