Freshwaterhack Project: Groundwater Resources and GRACE

A common challenge in interpreting and validating remote sensing data is in comparing these data to direct observations on the ground. Often remotely sensed data will cover large regions and have different temporal and spatial sampling frequency than point observations derived in the field. This kind of analysis requires geospatial tools to enable resampling, assessment of spatial statistics and extrapolation of point data to broader regions. The integration of satellite missions (GRACE) with hydrology models for determining drought indicators and water levels has been done in the United States (Houborg, et al., 2012; Zaitchick et al., 2008) using data assimilation from sophisticated observatory networks that are not available, for example, in sub-saharan Africa. However, there are studies that have analyzed operational, technical, institutional, financial, and environmental predictors of functionality for groundwater access (well) data collected from over 25,000 community-managed handpumps in Liberia, Sierra Leone, and Uganda (Foster, 2013). Lahren and Cook (2016) code and analyze the reasons for failure in 250,000 water points in 25 countries and found that 30% of boreholes are not functioning, either for "technical or mechanical” reasons, or for "low quantity". According to the World Bank, water supply failure in Africa is estimated to “represent a lost investment in excess of $1.2 billion” (Bonsor et. al. 2015). Women and girls continue to be the world’s water collectors, spending a significant fraction of their time and energy on the task (Sorenson et al 2011, Graham et al 2016, Cook et al 2016). Can a planetary scale observational tool be used to understand groundwater access and vulnerability for domestic use in rural households? If so, we can further investigate and develop the GRACE for Girls project.

Research Questions

How much is hydrological scarcity contributing to handpump failure in Africa?

In areas where domestic water access is primarily through wells, are areas with non-functional wells because of low quantity observable with remote sensing data?
What spatial statistics can be used to understand the reasons for well failure using geolocated water points and falling groundwater levels?

Sample data

Point data: The Water Point Data Exchange (WPDx) is a global platfrom for sharing water point data to understand water services with 240,000 + water points in the dataset with the quantity of data varying between government support for complete datasets (all 101,000 water points in Uganda) as well as data in other countries with known GRACE observable groundwater levels (India).

The WPDx data downloaded in February 2016, and coded for well failure due to water resources issues (Lahren and Cook (2016)), is provided on Hydroshare. Go to Collaborate. Ask to Join Freshwater Group. Click on link for Freshwaterhack of UWGeohackweek. Go to Collection Contents. Click on Freshwaterhack Project: Groundwater Resources and GRACE

Remote sensing data: The Gravity Recovery and Climate Experiment (GRACE, a joint mission of NASA and the German Aerospace Center) measures the Earth's gravity anomalies to study how mass is distributed around the planet and used for studying Earth's eceans, geology, and climate.

GRACE land are available at http://grace.jpl.nasa.gov, supported by the NASA MEaSUREs Program.
D.N. Wiese. 2015. GRACE monthly global water mass grids NETCDF RELEASE 5.0. Ver. 5.0. PO.DAAC, CA, USA. Dataset accessed [YYYY-MM-DD] at http://dx.doi.org/10.5067/TEMSC-OCL05.

Watkins, M. M., D. N. Wiese, D.-N. Yuan, C. Boening, and F. W. Landerer (2015), Improved methods for observing Earth’s time variable mass distribution with GRACE using spherical cap mascons, J. Geophys. Res. Solid Earth, 120, doi:10.1002/2014JB011547.

在解读与验证遥感数据方面，一个普遍的挑战在于将这些数据与地面直接观测结果进行对比。通常，遥感数据会覆盖广阔的区域，其时空采样频率与现场获取的观测点数据存在差异。此类分析需要地理空间工具以实现重采样、空间统计评估以及将点数据外推至更广泛的区域。在美国，通过将卫星任务（GRACE）与水文模型结合，用于确定干旱指标和水位，已经实现了对从利比里亚、塞拉利昂和乌干达超过25,000个社区管理的手动水泵收集的地下水（井）数据的功能性预测因素（操作、技术、制度、金融和环境）的分析（Houborg等人，2012；Zaitchick等人，2008），这些分析使用了复杂的观测网络进行数据同化，而这些网络在例如撒哈拉以南非洲地区并不具备。然而，也有研究分析了来自利比里亚、塞拉利昂和乌干达超过25,000个社区管理手动水泵的地下水数据的功能性预测因素，这些数据包括操作、技术、制度、金融和环境因素（Foster，2013）。Lahren和Cook（2016）对25个国家250,000个水点的失效原因进行了编码和分析，发现其中30%的水井因“技术或机械”原因或“水量低”而无法正常工作。据世界银行估计，非洲的水供应失败“代表超过12亿美元的损失投资”（Bonsor等人，2015）。妇女和女孩继续担任全球的水收集者，她们花费了大量的时间和精力来完成这项任务（Sorenson等人，2011，Graham等人，2016，Cook等人，2016）。是否可以使用行星尺度的观测工具来理解农村家庭对地下水的获取和脆弱性？如果是这样，我们可以进一步调查和开发GRACE for Girls项目。

研究问题

水文稀缺对非洲手动水泵的失效贡献了多少？
在家庭用水主要通过井的地区，非功能性水井是否可以通过遥感数据观察到水量低的情况？
可以使用哪些空间统计来理解使用地理定位水点和地下水位下降原因的水井失效？
样本数据

点数据：水点数据交换（WPDx）是一个全球平台，用于共享水点数据以了解水服务，数据集中包含超过240,000个水点，数据量因各国政府支持完整数据集（乌干达的101,000个水点全部）以及已知GRACE可观测的地下水位的其他国家（印度）而异。

2016年2月下载的WPDx数据，并针对因水资源问题导致的水井失效进行了编码（Lahren和Cook，2016），可在Hydroshare上提供。前往“合作”。请求加入淡水组。点击UWGeohackweek淡水黑客链接。前往“收藏内容”。点击淡水黑客项目：地下水资源和GRACE。

遥感数据：重力恢复与气候实验（GRACE，美国宇航局与德国航空航天中心的联合任务）测量地球重力异常，以研究质量在地球周围的分布情况，并用于研究地球的海洋、地质和气候。

GRACE陆地数据可在http://grace.jpl.nasa.gov获取，由NASA MEaSUREs项目支持。
D.N. Wiese. 2015. GRACE月度全球水质量网格NETCDF发布5.0。版本5.0。PO.DAAC，CA，USA。数据访问日期[YYYY-MM-DD]在http://dx.doi.org/10.5067/TEMSC-OCL05。
Watkins, M. M., D. N. Wiese, D.-N. Yuan, C. Boening, and F. W. Landerer (2015)，使用球形帽质量体改进GRACE观测地球时间变量质量分布的方法，地球物理研究杂志，固体地球，120卷，doi:10.1002/2014JB011547。