Water data science

The USDA Natural Resources Conservation Service (NRCS) developed the Mississippi River Basin Healthy Watersheds Initiative (MRBI) program to improve the health, water quality and wildlife habitat within the Mississippi River Basin. Lake Conway Point Remove (LCPR) watershed was identified as one of the watersheds for the MRBI program implementation. The goal of this paper is to evaluate the effectiveness of the MRBI program in LCPR watershed using a computer simulation model. Seven best management practices (BMPs) (pond, wetland, pond and wetland, cover crops, vegetative filter strips, grassed waterways and forage and biomass planting) were modelled under four placement strategies: random placement in 30% of the watershed, random placement in 30% hydrologic response units (HRUs) of the high priority hydrological unit code (HUCs), placement in the top 30% of the high priority HUCs, and top 30% of the HRUs in the HUCs near the outlet of the watershed. The model was calibrated for flow for the period 1987–2006 and validated for the period 2007–2012. Sediment and nutrients were validated from 2011 to 2012. Out of the BMPs evaluated, grassed waterways proved to be the most effective BMP in reducing sediment and nutrient loads from row crop (soy beans) and pasture fields. Reductions at the watershed outlet ranged 0–1% for flow, 0.28–14% for sediment, 0.3–10% for TP and 0.3–9% for TN. Relatively higher reductions were observed at the subwatershed level, flow reductions ranged 0–51%, sediment reductions -1 to 79%, TP -1 to 65% and TN -0.37 to 66% depending on BMP type, placement scenario, and watershed characteristics. The results from this study provide the data to help prioritize monitoring needs for collecting watershed response data in LCPR and BMP implementation evaluations, which could be used to inform decisions in similar studies.

This study focuses on Laos, a landlocked nation located in South-East Asia with sub-tropical climate and highly seasonal rainfall distribution. Laos is one of the world’s least developed countries, and currently witnesses an unprecedented level of development that is highly reliant on its natural resources, including groundwater. There is currently very limited data and no nationwide assessment of shallow (lt;30 m) groundwater resources to support sustainable management. This study provides a first step towards addressing this issue by (i) identifying the major aquifer units of the country; (ii) integrating localized data and regional maps into an assessment of the groundwater potential; and (iii) producing quantitative maps of key hydrogeological indicators. Eight aquifer units have been described and evaluated: (i) Basement aquifers, (ii) Volcanic aquifers, (iii) Schists, (iv) Paleozoic sedimentary, (v) Karsts, (vi) Limestones, (vii) Mesozoic sedimentary and (viii) Alluvial sediments. The Mesozoic sandstones and the Alluvial aquifers are the most extensive and productive hydrogeological systems in the country. The Volcanic and Karstic aquifers, although poorly known, might also have important potential. This assessment, along with the maps of quantitative aquifer indicators, provide a significant improvement in both spatial resolution and accuracy compared to previously available information. It will likely support improved management plans and the identification of areas with higher potential for groundwater development.

Laos has vast surface water resources. However, in areas located far away from surface water sources or those that are prone to surface water scarcity, groundwater is gaining recognition as a valuable source of water for agricultural development. Households in Ekxang village on the Vientiane Plain, for example, depend on rainfall for the cultivation of rice during the wet season and a wide range of vegetables and herbs in the dry season. Climate change poses a growing threat to crop production in such villages, altering wet season rainfall and making drought more common and severe. To help find a new way forward, a 2-year pilot study of groundwater irrigation was carried out in Ekxang to assess the technical performance, economic viability and effectiveness of the institutional arrangements. Participation in the pilot was quite modest due to farmers being wary of possible risks related to the costs of the new irrigation system. As farmers gained experience with the high-performance pumps and other equipment, their trust grew, and they came to have a sense of ownership over the system. The irrigation system turned out to be profitable for dry-season irrigation of cash crops. Growing rice under these conditions proved to be unprofitable. Increased profits, however, did not translate into increased popularity. In the pilot’s second year, with the subsidy removed, participation in the groundwater users group declined. Apart from the additional cost for pumping, another reason was a lack of household labor to manage the production of cash crops under groundwater irrigation. This, in turn, stemmed from the availability of other livelihood options (such as small businesses and wage labor), which compete with agriculture and may prove more appealing. Clearly, the future development of such systems will depend, not just on local hydrogeological conditions, but also on a better understanding of the social and economic factors that influence farmers’ decisions. New technologies could make a difference as well, such as solar pumps, which likely reduce farmers’ production costs. Lessons learned from this pilot study should prove valuable for helping realize the potential of groundwater irrigation in Laos.