Evaluation of Climate Change-Induced Impact on Streamflow and Sediment Yield of Genale Watershed, Ethiopia

In the 21st century, changes in induced climate can significantly affect the water resources system in the watershed. Understanding climate change disrupts hydrological processes can facilitate sustainable water resource strategies to resilient impacts of global warming. The hydrological response of watersheds will be accelerated by climate change, altering the rainfall, magnitude & timing of runoff, and sediment yield. The study investigates climate change aspects on the hydrological responses using Soil and Water Assessment Tool (SWAT) model interfaced with Geographical Information System (GIS) of Genale Basin, Ethiopia. The calibrated SWAT was applied to simulate the impact of climate, and the SUFI-II algorithm was used for parameter optimization & finalization. The change of climate scenarios was built using the outcomes bias-corrected CORDEX RCM daily precipitation, min/max temperature for Ethiopia under RCP 4.5 and RCP 8.5. The average monthly change of streamflow from −16.47% to 6.58% and − 3.6% to 8.27% under RCP4.5 and RCP8.5, respectively (2022–2080). The monthly average sediment yield change was −21.8% to 6.2% and − 5.6% to 4.66% for the RCP4.5 and RCP8.5 scenarios, respectively, over 2022–2080. It implies that the climate change-induced impacts on sediment yield are more significant than streamflow and suggest substantial adaptive management in watershed systems

A modified hydrodynamic model for routing unsteady flow in a river having piedmont zone

Existence of piedmont zone in a river bed is a critical parameter from among numerous variations of topographical, geological and geographical conditions that can significantly influence the river flow scenario. Downstream flow situation assessed by routing of upstream hydrograph may yield higher flow depth if existence of such high infiltration zone is ignored and therefore it is a matter of concern for water resources planning and flood management. This work proposes a novel modified hydrodynamic model that has the potential to accurately determine the flow scenario in presence of piedmont zone. The model has been developed using unsteady free surface flow equations, coupled with Green-Ampt infiltration equation as governing equation. For solution of the governing equations Beam and Warming implicit finite difference scheme has been used. The proposed model was first validated from the field data of Trout Creek River showing excellent agreement. The validated model was then applied to a hypothetical river reach commensurate with the size of major tributaries of Brahmaputra Basin of India. Results indicated a 10% and 14% difference in the maximum value of discharge and depth hydrograph in presence and absence of piedmont zone respectively. Overall this model was successfully used to accurately predict the effect of piedmont zone on the unsteady flow in a river

A few simple CFD models for flow simulation around groyne

The flow processes around a groyne structure is a complex and challenging topic in computational hydraulics and has brought attention of many researchers in the last few decades. In comparison to experimental studies, numerical modeling can provide more details about the flow characteristics at less cost. In the present work, performances of four simple finite difference schemes, i.e., Lax diffusive scheme, predictor corrector scheme, modified predictor corrector scheme and Beam and Warming scheme are compared in simulation of flow around groyne structure. The numerical results are validated with available experimental data and the best model is found out in terms of accuracy and efficiency

Retrospection of Outbreaks of <i>Spodoptera mauritia </i>Boisduval in NER India: The Solution Lies in Ecological Engineering, Not in Insecticides

Rice cultivation in North East India is organic by tradition; however, the recent outbreaks of the rice-swarming caterpillar, Spodoptera mauritia Boisduval, have compelled rice-farmers to use synthetic insecticides. The outbreak in 2016 affected more than 56,768 ha of winter rice in 28 districts of Assam. About 25,545–42,576 L insecticide was applied in the state to combat the outbreak. This is one of the highest insecticide loads ever to be added to the rice ecosystem of Assam. Such a load, if added repeatedly with the reoccurrence of outbreaks, may affect the innate resilience of the rice ecosystem in the long run. In this paper, the outbreak of RSC has been analysed from an ecological perspective in order to replace the existing policy of exclusive dependence on insecticide. The review will help the researchers, extension workers and policy makers of the rice producing countries, more specifically in Asian countries, which together account for more than 91% of the world’s rice production

Cost-Effective Optimization of Nature-Based Solutions for Reducing Urban Floods Considering Limited Space Availability

The conventional urban stormwater management practices focus on carrying away runoff quickly by lined conveyors, which increase the surface runoff and reduce the time of concentration, subsequently causing floods in downstream areas. Ecological Management Practices (EMPs) provide nature-based solutions for reducing flood risks in a sustainable and economically viable manner. However, in the rapidly urbanizing setups in developing nations, the application of EMPs is limited due to space availability, data scarcity and limited funding. This study uses a Non-Linear Programming Optimization Technique to provide modelling solutions in optimizing the land-use and costs under EMPs to reduce flood risks in the Quebrada Aries watershed in the Municipality of Heredia in Costa Rica. Depending on the availability and ease of execution, a combination of three EMPs (bio-retention areas, infiltration trenches and green roofs) were tested. The effect of the application of derived optimal combinations has been analysed. The optimal combination of EMPs analysed for different channel capacity was able to reduce the peak discharge for the worst flood causing event of 50 years return period from 16.86 m3/s (under current land-use) to 9 m3/s, 9.51 m3/s, 8.38 m3/s and 9.13 m3/s in four hypothetical scenarios considered. In urbanized catchments, EMPs cannot be applied indefinitely to avoid floods. However, an optimal combination of EMPs can drastically reduce the requirement of large capacity drainage channels. This information can help policy-makers to analyse trade-offs between urban development and flood control measures. The study is suitable for other data-scarce regions as well

Retrospection of Outbreaks of Spodoptera mauritia Boisduval in NER India: The Solution Lies in Ecological Engineering, Not in Insecticides

Rice cultivation in North East India is organic by tradition; however, the recent outbreaks of the rice-swarming caterpillar, Spodoptera mauritia Boisduval, have compelled rice-farmers to use synthetic insecticides. The outbreak in 2016 affected more than 56,768 ha of winter rice in 28 districts of Assam. About 25,545–42,576 L insecticide was applied in the state to combat the outbreak. This is one of the highest insecticide loads ever to be added to the rice ecosystem of Assam. Such a load, if added repeatedly with the reoccurrence of outbreaks, may affect the innate resilience of the rice ecosystem in the long run. In this paper, the outbreak of RSC has been analysed from an ecological perspective in order to replace the existing policy of exclusive dependence on insecticide. The review will help the researchers, extension workers and policy makers of the rice producing countries, more specifically in Asian countries, which together account for more than 91% of the world’s rice production

Comparative study of norepinephrine and phenylephrine infusion for prophylaxis against post-spinal hypotension in patients undergoing elective cesarean section

Background: Maternal hypotension is a physiological response during cesarean section (CS) with spinal anesthesia (SA) and can cause adverse maternal and fetal outcomes. Aim: The present study aimed at comparing the efficacy and safety of norepinephrine and phenylephrine infusion in a CS under SA. Methods: In a randomized clinical trial, 164 ASA I and II parturients undergoing CS under SA were randomized to have a prophylactic infusion of norepinephrine 0.05 µg/kg/min (group N) or phenylephrine 0.75µg/kg/min (group P). The primary outcome was the incidence of post-spinal hypotension. Incidence of severe post-spinal hypotension, reactive hypertension, and bradycardia, total vasopressor rescue bolus doses required, number of physician interventions, nausea and vomiting, and Apgar score at 1 and 5 mins were secondary outcomes. Results: The incidence of post-spinal hypotension in group P (24 %) and group N (29.26 %); severe post-spinal hypotension in group P (3.6 %) and group N (2.4%) respectively and were comparable (p-value >0.05). No of bolus dose of vasopressor required between the two groups, and the incidence of bradycardia and reactive hypertension were comparable. Nausea and vomiting were very low in both groups and comparable. The number of physician interventions needed was significantly higher in group P (39.02%) compared to group N (28.04%) (p-value < 0.05). Conclusion: Norepinephrine is associated with a lower number of physician interventions as compared to phenylephrine; otherwise, hemodynamics is comparable when used to prevent hypotension