Progress 10/01/12 to 09/30/13
Outputs
Progress Report Objectives (from AD-416): Determine the rates of potential groundwater recharge in the sugar cane production system including seepage from irrigation canals and reservoirs. Seepage in these areas is critical for recharging aquifers that supply water to the Island of Maui. Quantifying the rates of recharge is needed to assess water supplies for potential biofuels production. Approach (from AD-416): Categorize the existing 75 miles of irrigation canals by similar soils, geology, and slope and whether the canal is lined or unlined. Within specific sample areas of similar geology, slope, soils, and canal type (line or unlined), use geophysical methods to assess potential for seepage. In areas of potentially high seepage, install seepage meters to give more quantitative rates of water loss within the canal system. The Navy's dependence on oil (petroleum) strains operational planning. Its focus is on securing a sustainable fuel supply. ARS research and models are helping determine best management of natural resources to allow Office of Naval Research (ONR) sustainability in fuel supply while also promoting ecological services and the local economy in Hawaii. Efficient water management in sugarcane production requires an understanding of water losses. In cooperation with scientists at Baylor University and Texas AgriLife Research, seepage under irrigation canals and water supply reservoirs has been identified as potential sources of water loss. A geophysical technique called resistivity was applied to six irrigation reservoirs at varying elevations and geology to determine areas of active seepage. Initial results showed a perched water table approximately 3 feet to 20 feet from the surface. To quantify the rate of seepage, a seepage meter was designed, developed, and applied to the six reservoirs that were analyzed using resistivity. Contrary to current understanding, all reservoirs showed a net influx of water, shifting focus on management of the perched water table to minimize seepage losses. This past year three more reservoirs were surveyed. A ponding study was conducted on a large reservoir underlain with sandy soils. The results showed seepage occurred but at one-third of the previously estimated rate. Also, state-of-the-art Doppler flow meter technology was tested on six canal lengths to determine seepage losses under the canals. With accuracy within 5-10%, the methodology is well suited to stream flow measurements; however, the accuracy may not be adequate for estimating losses in canals. The method is currently being refined to determine if it may provide realistic seepage losses in the canals. Quantifying reservoir and canal losses will allow more efficient management of irrigation water and more sustainable biofuel production in Hawaii.
Impacts
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Publications
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Progress 10/01/11 to 09/30/12
Outputs
Progress Report Objectives (from AD-416): Determine the rates of potential groundwater recharge in the sugar cane production system including seepage from irrigation canals and reservoirs. Seepage in these areas is critical for recharging aquifers that supply water to the Island of Maui. Quantifying the rates of recharge is needed to assess water supplies for potential biofuels production. Approach (from AD-416): Categorize the existing 75 miles of irrigation canals by similar soils, geology, and slope and whether the canal is lined or unlined. Within specific sample areas of similar geology, slope, soils, and canal type (line or unlined), use geophysical methods to assess potential for seepage. In areas of potentially high seepage, install seepage meters to give more quantitative rates of water loss within the canal system. The Navy's dependence on oil (petroleum) strains operational planning. Its focus is on securing a sustainable fuel supply. ARS research and models will help determine how best to manage natural resources to allow Office of Naval Research (ONR) sustainability in fuel supply while also promoting ecological services and the local economy in Hawaii. Seepage under irrigation canals and water supply reservoirs has been identified as potential sources of water loss. A geophysical technique called resistivity was applied to six irrigation reservoirs at varying elevations and geology to determine areas of active seepage. Initial results show a perched water table approximately 3 feet to 20 feet from the surface that flows downslope. To quantify the rate of seepage, a seepage meter was designed, developed, and applied to the six reservoirs that were analyzed using resistivity. Contrary to current understanding, all reservoirs showed a net influx of water, shifting focus on management of the perched water table to minimize seepage losses. Also, state-of-the-art doppler flow meter technology is being tested on canals to determine seepage losses. The methodology is currently being developed and refined for conditions on the HC&S (Hawaiian Commercial & Sugar Company) plantation.
Impacts
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Publications
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Progress 10/01/10 to 09/30/11
Outputs
Progress Report Objectives (from AD-416) Determine the rates of potential groundwater recharge in the sugar cane production system including seepage from irrigation canals and reservoirs. Seepage in these areas is critical for recharging aquifers that supply water to the Island of Maui. Quantifying the rates of recharge is needed to assess water supplies for potential biofuels production. Approach (from AD-416) Categorize the existing 75 miles of irrigation canals by similar soils, geology, and slope and whether the canal is lined or unlined. Within specific sample areas of similar geology, slope, soils, and canal type (line or unlined), use geophysical methods to assess potential for seepage. In areas of potentially high seepage, install seepage meters to give more quantitative rates of water loss within the canal system. The Navy's dependence on oil strains operational planning. Its focus is on securing a sustainable fuel supply. ARS research and models will help determine how best to manage natural resources to allow Office of Naval Research (ONR) sustainability in fuel supply while also promoting ecological services and the local economy in Hawaii. Seepage under irrigation canals and water supply reservoirs has been identified as potential sources of water loss. An extensive literature review was conducted to determine available and appropriate field techniques to estimate seepage under canals and reservoirs. A resistivity method was tested on a representative reservoir and canal section to determine areas of active seepage. Seepage meters were designed to quantify seepage rates under areas identified as leaking using the resistivity testing. The seepage meters will be tested and applied next year on the HC&S (Hawaii Commercial & Sugar Company) sugar plantation in Maui. The ADODR monitored progress through regular emails and phone calls with the collaborator.
Impacts
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Publications
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