Environmental Science and Management

Background Assessing the influence of climate change on the crop growth period, water requirement, and drought conditions is important for the integrated planning of the production system. This study assessed the impact of climate models from the Coupled Model Inter-comparison Product (CMIP5) on Crop Water Requirement (CWR), Length of Growth Period (LGP), and drought conditions. This study applied two regional climate models that have shown better performance for the evaluation criteria during the historical period. Drought analysis was conducted for different classes of drought index using standardized anomalies of rainfall (S-index) from climate models. Results The future growing season of the area on average for all the years is between April 15 and May 1. The period between April 15 and May 1 marks the onset time and the end of September is the cessation time having LGP ranging from 150–160 days. Crop water requirement was projected to increase on average from the base period on...

Characterization of watershed hydrological process is vital for sustainable water resource management. The principal goal of this study was to investigate the inference of drainage attributes on basic hydrological processes using spatial-based morphometric analysis on Tikur Wuha river watershed. The result obtained indicated that the area was characterized with fifth-order stream. Drainage area with higher stream order has lower infiltration capacity, and the shorter stream lengths were associated with the steepness of the area which affects water flow. Based on Nu value, sub-watersheds were categorized in the active erosion stage (SW7) and matured topography development (SW6). The interpretation from watershed geometry identified circular areas most susceptible to rapid hydrological response (SW11). Hydrological process and underlying materials are mainly correlated with the drainage texture parameter, and the lower the values indicated less rocky terrain and very high infiltration...

Quantifying uncertainties in water resource prediction in data-scarce regions is essential for resource development. We use globally available datasets of precipitation and potential evapotranspiration for the regionalization of model parameters in the data-scarce regions of Ethiopia. A regional model was developed based on 14 gauged catchments. Three possible parameter sets were tested for regionalization: (1) the best calibration parameters, (2) the best validation parameter set derived from behavioral parameters during the validation period, and (3) the stable parameter sets. Weighted multiple linear regression was applied by assigning more weight to identifiable parameters, using a novel leave-one-out cross-validation technique for evaluation and uncertainty quantification. The regionalized parameter sets were applied to the remaining 35 ungauged catchments in the Ethiopian Rift Valley Lake Basin (RVLB) to provide regional water balance estimations. The monthly calibration of th...

We thank Reviewer 1 for the thoughtful suggestions and constructive comments that we believe highly strengthening the quality of our study. We structured our responses directly below each reviewer comment in bold font. 1. The literature review is quite outdated. Many seminal papers are presented in this paper, but a lot of work has been done in the past few years that could be used to set a clearer context to this study. For example, see Guo et al. 2021 for an up-to-date review on regionalization approaches across the globe. This will also help contextualize the claim in lines 57-59:

This is a review of “Quantifying the Regional Water Balance of the Ethiopian Rift Valley Lake Basin Using an Uncertainty Estimation Framework” by Abraham et al. The paper presents a method to predict streamflow on ungauged basins in a region of Ethiopia. The method first uses behavioral parameter sets to identify parameters that are to be used in the regression analysis (for identifying relationships between parameters and catchment descriptors). A few parameter selection methods are proposed, which are then tested in regionalization using a leave-one-out approach. The authors then extend the study to include an analysis on the streamflow elasticity to better understand how changes in precipitation can affect variations in streamflow.

Data scarcity in many areas around the world represents a major problem for hydrological model calibrations. Global parameter estimates and global forcing can provide possibilities to access hydrological responses in ungauged regions. In this study, we applied HBV global parameter estimates considering uncertainty in the Upper Neckar and Upper Danube catchments, Germany, to answer what are the influencing factors and how good are their local applications. We tested simulations with precipitation in spatial resolutions from 0.05 to 0.2° and with local/global sources. Results show that the general performance is acceptable to good (Kling-Gupta efficiency, KGE: 0.51–0.79) in both catchments using local or global precipitation. The influence of spatial resolutions is insignificant while using local precipitation slightly increases performance in both catchments. Catchment properties such as complex topography and special karst subsurface may lead to a deterioration of performance by 0.2...

This study investigated the use of effective microorganisms (EM) to enhance cost-effective biogas purification at household-level application. It involved experimental setups for biogas purification in two different runs: 4 L activated EM and 1 L dormant EM by bubbling biogas through EM purification units. Biogas composition was analyzed using an industry-standard biogas analyzer. The results indicated that EM has the potential for biogas purification through a biological process, to remove H 2 S and CO 2 by involving photosynthetic bacteria (Rhodopseudomonas palustris) in the presence of light. The raw biogas average composition was 62.2% CH 4 , 37.4% CO 2 and 1359.3 ppm H 2 S. The 4L activated EM batch solution purified the raw biogas to 80.2% CH 4 , 19.5% CO 2 and 786.1 ppm H 2 S. The corresponding purification efficiencies are 60% for CO 2 and 49% for H 2 S. Purified biogas could be used by the household to cook for 1.82 h (85%) while raw biogas could cover only 55%. The designed biogas purification system can cost only Tshs 91,010/= and purify about 15,000 L of biogas at EM cost of Tshs 9,100/month.

The study investigates the potential of coconut husks in purifying biogas, a common issue in the use of biogas due to the high costs and environmental impact of expensive purification technologies. The study used an experimental setup generating biogas from kitchen waste and analysed its composition using an industry-standard biogas analyser. Coconut husks could remove hydrogen sulphide (H 2 S), with a high percentage removal efficiency of 54% at a column length of 0.5 m from the inlet. Based on the results, 2 kg of coconut husk could purify 837 L of biogas, with a removal efficiency of approximately 62%, before exhaustion. This suggests that coconut husks can be used in biogas purification to remove H 2 S, which is the most challenging component as it can corrode metal parts when used at high concentrations above 750 ppm. Further research is needed on large-scale purification using coconut husks at high pressure to allow more gas adsorption by the purification media.