# A Review of In-Situ and Remote Sensing Technologies to Monitor Water and Sanitation Interventions
## 2 Sensing WASH
### Satellite Remote Sensing  
Remote sensing capabilities and techniques are well suited for the monitoring of regional-scale precipitation, water budgets, soil moisture, and some measures of water quality. Other possible satellite imagery and remote sensing applications include catchment characterization, water quality monitoring, soil moisture assessment, water extent and level monitoring, irrigation service monitoring, urban and agricultural water demand modeling, evapotranspiration estimation, ground water management, hydrological modeling, and flood mapping/forecasting. Various satellite data products have been leveraged to aid water and sanitation programs. Key examples include:  
* The Sentinel-1 Program for water management in low-income countries was part of a large research initiative that explored the performance and opportunities provided by the European satellite Sentinel-1 for water resource management applications. The satellite data was used to estimate water volumes retained by small reservoirs to assess the feasibility of small water supply systems [10]. * In particular, LandSat 8 data allow for a calculation of the Normalized Differential Vegetation Index (NDVI). The LandSat 8 NDVI allows an estimation of land surface emissivity [11] and land cover classification [12], as well as surface temperature. These measures can be used by remote sensing experts to allow a planning-level estimation of watershed health across a broad region. Additionally, land use classification can identify the vegetation and population densities of rural versus urban, built environments. * SERVIR, a cooperative effort of NASA and the United States Agency for International Development (USAID), \"works in partnership with leading regional organizations world-wide to help developing countries use information provided by Earth observing satellites and geospatial technologies for managing climate risks and land use\" [13]. With three regional offices, SERVIRhas been able to partner with remote sensing experts and national decision-making bodies. Among other activities, SERVIR focuses on monitoring water bodies to observe effects from \"human activities, climate change, and other environmental phenomena\". It takes advantage of LandSat, ASTER, MODIS, and other satellite assets to monitor water quality and changes. Specifically, SERVIR is developing rainfall and runoff models to study the availability and quality (as sediment or total dissolved solids) of surface water over the next several decades. * Using the Tropic Rainfall Measuring Mission (TRMM) data, the Nile Basin Initiative in partnership with NASA provides flood forecasts and water balance estimates for the Eastern Nile Basin. Similarly, the Surface Hydrology Group at Princeton University developed the Africa Drought Monitor and provides maps of rainfall, temperature, and other hydrologic variables [14]. * The USAID Famine Early Warning System Network (FEWS) monitors rainfall and crop production with satellite assets and combines these data with socioeconomic insights to identify population groups that may be vulnerable to food insecurity [15]. * NASA's Terra satellite includes two instruments that have been leveraged for watershed monitoring. The Moderate Resolution Imaging Spectroradiometer (MODIS) and the Multiangle Imaging Spectroradiometer (MISR) satellite assets can be used to determine aerosol optical depth, land surface temperature, enhanced vegetation index, and middle infrared reflectance. Some of these data can be used to assess water quality parameters including chlorophyll, cyanobacterial pigments, colored dissolved organic matter, and suspended matter in water bodies on a large scale [15]. * In Nigeria, the World Bank recently used geographic information system (GIS) mapping techniques to compare household survey data against MODIS land use estimates to generate spatial distribution estimates of water and sanitation indicators, including service access [16].