Re-posted from GroFutures.org
The GroFutures team at Sokoine University of Agriculture (SUA, Tanzania), led by Japhet Kashaigili (SUA) with support from PhD students, Hezron Philipo (SUA) and David Seddon (UCL), established in July (2017) a groundwater-level monitoring network in the Upper Great Ruaha Basin Observatory in southern highlands of Tanzania. This area is part of the Southern Agricultural Growth Corridor of Tanzania (SAGCOT) where increased use of groundwater and surface water is anticipated to support agricultural production. Constructed monitoring wells at depths ranging from 18 to 32 m below ground were drilled using a PAT-DRILL 421 rig. The team also instrumented monitoring wells recently constructed by project partners at the Rufiji Basin Water Board (RBWB) in the Tanzanian Ministry of Water and Irrigation.
The new monitoring network comprises an upstream location at Chimala at the base of an escarpment and a downstream location at Mbarali within the alluvial plain. A monitoring well at Chimala Secondary School was installed into coarse unconsolidated sands and gravels to a depth of 26 m. This monitoring well is linked to both an additional monitoring well at Usangu Secondary School and a river gauge. Both monitoring wells are equipped with automated dataloggers providing hourly groundwater-level measurements. A third borehole was constructed at Chimala Primary School though no groundwater was encountered up to a depth of 30 m. At Mbarali, two monitoring wells were constructed on the St. Ann’s Secondary School and now form a transect of 4 monitoring wells as the team also instrumented two monitoring wells recently constructed by the RBWB at Rujewa at Mbarali Secondary School and Jangurutu Primary School.
The new infrastructure is expected to reveal for the first time the dynamics between groundwater and surface water in the Upper Great Ruaha sub-catchment of the Rufiji Basin and answer key questions around the nature of groundwater recharge and whether seasonal river flow recharges groundwater or groundwater sustains river flow. Further work will also seek to ensure that this observatory is equipped with both tipping-bucket rain gauges to record sub-daily (hourly) rainfall intensities and soil-moisture probe arrays to better understand how intense rainfalls are transmitted through alluvial soils.
reposted from: http://grofutures.org/article/grofutures-at-awac-2016-in-tanzania/
Professor Japhet Kashaigili presented recent research from the GroFutures Site Observatory in Tanzania (Makutapora) at the 4th Annual Conference (AWAC 2016) of the Association of Tanzanian Water Suppliers (ATAWAS) held on 8th and 9thNovember 2016 in Dodoma, Tanzania. Under the theme of “Knowledge, Capacity and Learning in the Water and Sanitation Sector,” the development of water supplies and sanitation as well as the current challenges faced by organisations across Tanzania were discussed by professionals working in water sector including policy makers and those involved water governance.
Professor Japhet Kashaigili, based at Sokoine University of Agriculture (SUA), presented a paper entitled, Assessing the sustainability of groundwater-fed water supplies to intensive pumping and climate variability: evidence from detailed monitoring of the Makutapora Wellfield, drawing on collaborative research conducted by SUA, University College London, University of Sussex (UK), and the WamiRuvu Basin Water Board within the Ministry of Water and Irrigation. Key stakeholders including the Dodoma Regional Administrative Secretary and Technical Manager of the Dodoma Urban Water Supply and Sanitation Authority (DUWASA) expressed great interest in the GroFutures Team’s evaluation of the sustainability of intensive groundwater abstraction from the Makutapora Wellfield, which is currently the sole perennial supply of freshwater to the rapidly growing capital city, Dodoma. Japhet’s presentation highlighted the bias in wellfield replenishment (recharge) to heavy rainfall and the observed dependence of recharge on the duration of ephemeral river discharge to the wellfield. He also reported on the establishment of telemetry-based, high-frequency (hourly) monitoring of groundwater levels in boreholes enabling the WamiRuvu Basin Water Board and GroFutures team to download real-time monitoring of groundwater levels for wellfield management and research.
The GroFutures team is working with the Tanzanian Ministry of Water to establish automated, high-frequency monitoring to examine how heavy rains associated with the El Niño Southern Oscillation (ENSO) replenish vital groundwater resources.
The team from Sokoine University of Agriculture (Japhet Kashaigili, PhD student Richard Festo) and UCL (Richard Taylor, PhD Student David Seddon) are working with the WamiRuvu Basin Water Office in a small semi-arid basin (Makutapora) in central Tanzania which features a wellfield that supplies the capital city, Dodoma, with safe water. Groundwater withdrawals have risen sharply in recent years and there is considerable uncertainty regarding the sustainability of this supply. Previous research led by members of the GroFutures Team showed that replenishment occurs episodically, on average just 1 year in 5, and usually in association with El Niño events.
In anticipation of the “Godzilla” El Niño event this year, the team is setting up instruments to monitor hourly groundwater levels and river stage (level) to investigate how heavy rains replenish groundwater at the Makutapora Wellfield. These observations will inform not only sustainable management of wellfield itself but also strategies for amplifying replenishment here and in other similar tropical semi-arid locations.