regulated streamflowregulating gateregulationrehabilitationrejection surgerelative densityrelative evaporationrelative frequencyrelative heightrelative humidityrelative initial depthrelative roughnessrelative sequent depthrelative vorticityreleaserelictionreliefremidal actionremote sensingrendzinareno mattresrepelling groinreplacement flowreplicationreplogle flumereqular stream linesrescalerescalingreservior strippingreservoirreservoir capacityreservoir liningreservoir routingreservoir siltingresidence timeresident timeresidual effectresidual errorresidual fertilityresidual managementresidual rainresidual soilresidual variationresources inventoryresulationretained waterretainig basinretaining wallretardanceretardance coefficient