Irrigation Schemes Research Articles

Comparative Study of the Efficacy of Two Biological Insecticides (Azadirachta indica and Bacillus thuringiensis) and a Chemical insecticide (Diflubenzuron WP) against Fall Armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae) in Maize Crop, Western Bur

Aims: This study aimed at comparing the biological efficacy of Diflubenzuron WP, a chemical insecticide, and two biopesticides, one based on neem oil (Azadirachta indica) and an entomopathogen (Bacillus thuringiensis) against the fall armyworm on maize. Place and Duration of Study: The work was carried out on the irrigated scheme of Bama, western Burkina Faso during the 2022 and 2023 wet seasons. Methodology: The experimental design was a Fisher block with 4 treatments: T0: untreated or control; T1: Bacillus thuringiensis; T2: neem oil; T3: Diflubenzuron WP, in 4 replications. Entomological observations focused on the score and severity of attacks, as well as the pest's infestations rate. Results: The results showed that the different insecticides tested over the two wet seasons of 2022 and 2023 induced better control of S. frugiperda populations, with larval density being kept lower with the treatment of Diflubenzuron WP (4.25±1.2%), neem oil (14.28±1.6%) and Bacillus thuringiensis (24.5±3.2%). The insect damage severity rates and scores of damaged ears were also low for the three treatments respectively (1.09±0.2, 0.9±0.26 and 0.27±0.71) over the two cropping seasons. Diflubenzuron WP insecticide treatment not only reduced pest pressure, but also significantly improved maize yield. No surprisingly the highest yield (5.14 t/ha) was recorded with Diflubenzuron WP, followed by neem oil (4.62kg/ha) and finally Bacillus thuringiensis (3.92kg/ha). Conclusion: Further studies are needed to determine the optimal doses of neem oil and Bt for the control of Fall Armyworm. Neem oil can be considered as a good alternative to a chemical insecticide like Diflubenzuron WP.

Climate change adaptation benefits from rejuvenated irrigation systems at Kiwere and Magozi schemes in Tanzania

ABSTRACT We examine whether soil moisture and nutrient monitoring tools and Agricultural Innovation Platforms improve farmers adaptive capacity to climate change in the context of two small-scale irrigation schemes in Tanzania. Analysis of household surveys and farmer field books show that these interventions have significantly increased household income and diversification and reduced water use and conflicts. This has contributed to rejuvenating the schemes and increased the willingness to collaborate. Farmers within these schemes report less COVID-19 impact than farmers within surrounding schemes. We argue that the interventions have increased farmers’, and their communities’, resilience and capacity to adapt to climate change.

Current and potential distribution of the invasive apple snail, Pomacea canaliculata in Eastern Africa: evidence from delimiting surveys and modelling studies

The invasive apple snail Pomacea canaliculata has become a significant concern in invaded habitats beyond its native range. It was reported in Kenya in 2020 invading one of the largest rice-producing schemes, the Mwea irrigation scheme. Delimiting surveys were conducted across five key rice-producing schemes (Mwea, Bura, Hola, Ahero and West Kano) in Kenya to establish the extent of the invasion and develop effective quarantine and management strategies within the Mwea scheme and other risk areas. Additionally, the ensemble model approach was used to model the potential distribution of P. canaliculata in Eastern Africa (as defined by the United Nations Geoscheme). Over 80% of the Mwea scheme was infested with P. canaliculata, an expansion from the initial infestation point (Ndekia). The mean number of adults/m2 and egg clutches/m2 were 8.4 ± 0.9 (SEM) and 7.7 ± 1.4 (SEM), respectively, with varying densities across sections. No adults or eggs of P. canaliculata were found in the four schemes outside the Mwea scheme. The model predicted high suitability for P. canaliculata in the southwest of Kenya,and in coastal areas, with all surveyed areas marked as highly suitable.. Regionally, high-risk areas include Malawi, Madagascar, and Uganda. Mozambique, Tanzania, and Ethiopia showed localised areas of high suitability. Conversely, Sudan, South Sudan, Eritrea, Djibouti and Somalia were largely unsuitable for P. canaliculata. Given the potential for further spread, strict quarantine measures are essential to prevent the spread of P. canaliculata in Kenya and its introduction to uninvaded regions of Eastern Africa. Alongside this, implementing IPM e strategies is crucial for effective pest management and the protection of agricultural ecosystems.

The Changing Hydrology of an Irrigated and Dammed Yangtze River: Streamflow, Extremes, and Lake Hydrodynamics

AbstractUnderstanding the role of anthropogenic activities in the hydrological cycle is critical to support sustainable water management for the Yangtze River Basin (YRB), which experiences extensive dam operation, irrigation and water withdrawal. However, this remains challenging due to insufficient accuracies of existing process‐based models for fully depicting anthropogenic activities as part of the hydrological cycle. To this end, this study enhances a national‐scale coupled land surface‐hydrologic‐hydrodynamic model (CLHMS) with a dynamic irrigation scheme for distinct crops, an extended reservoir operation scheme incorporating both water storage anomalies and water demand anomalies, and a cost‐function‐based approach to link water demands with reservoir operation. The enhanced model is extensively validated against historical streamflow, water storage of 90 reservoirs, and irrigation water withdrawal in the YRB, and the water level and storage of the Poyang Lake (PYL). By setting up controlled experiments in the YRB, we show that the streamflow decreases by 2%–6% due to irrigation and water withdrawal, and manifests an attenuated seasonality due to reservoir operation. At the basin scale, the increasing trend of extreme flood peaks exhibits a reversal under human activities, with the flood mitigation effect of irrigation and water withdrawal accounting for up to 50% of that of reservoir operation. The hydrodynamics of the PYL also exhibits considerable human‐induced alterations, with a 1.79 m‐decrease in the water level at the end of flood season. Our study sheds light on quantifying anthropogenic hydrologic impacts at basin scales, with important implications for understanding the co‐evolution between anthropogenic activities and the hydrological cycle.

EFFECTS OF POLICY FACTORS ON TECHNICAL EFFICIENCY OF IRRIGATED RICE PRODUCTION UNDER DIFFERENT LAND ADMINISTRATION INSTITUTIONS DADIN KOWA IRRIGATION SCHEME, NIGERIA

The study was conducted to determine the effects of policy factors of land administration on the technical efficiency of irrigated rice production in the Dadin Kowa Irrigation Scheme (DKIS) area. A structured questionnaire was used for data collection. Three hundred and twenty irrigated rice farmers were selected using multi-stage sampling technique drawn from five land administration institutions in the DKIS area. Descriptive statistics, stochastic frontier, and multiple regression models were used to analyze the data. The technical efficiency (TE) analysis revealed that for the sample, farm size (P<0.01), fertilizers (P<0.05), herbicides (P<0.05), and pesticides (P<0.01) were all significant and negative while labour was positive (P<0.01). The inefficiency model for TE revealed that for the sample, four variables education, household size, access to improved seeds, and distance to market were each statistically significant at 5% probability level and negative (except for education which was positive). The effects of five policy factors of land administration (land governance, partnership in land use, socio-economic factors, gender and inclusiveness, institutional and environmental factors) on TE revealed that for the aggregate sample, only land governance (P<0.01) and socio-economic factors (P<0.05) were significant. The study recommended that the five policy factors of land administration should be accorded priority in strategic policy planning and implementation of programme for improving the productivity of irrigated agriculture and the livelihoods of people in the study area.

Multiscale spatial variability in land and water productivity across the Gezira irrigation scheme, Sudan

Agricultural performance assessment spans various spatial scales, from single plots to entire irrigation systems. A multi-scale analysis is thus crucial for informed decision-making. The Gezira irrigation sScheme in Sudan is a longstanding large-scale irrigation system experiencing severe water management challenges, manifested by low land productivity, water productivity, and irrigation efficiency. Recognizing the interdependence of decision-making, this research focuses on variations in water and land productivity at different spatial scales within the Gezira irrigation scheme. As one of the world’s largest gravity-irrigated systems, covering 2.1 million feddan (1 feddan = 0.42 ha ∼ 1 acre), the scheme serves as an interesting case to study head-tail performance variations across four spatial scales: tertiary, secondary, and major units, and the whole scheme. This study is centered on the winter season wheat cultivation 2022–2023, and employs the FAO’s Water Productivity Open Access Portal (WaPOR v2.1) datasets, with 100 m resolution, for computing land and water productivity. Ground-observed yield data from nine tertiary units (nimras) in the Wadelbur irrigation division were used to validate WaPOR. The results showed a systematic underestimation of WaPOR derived land productivity by about 40 % compared to the ground dataset. The head-tail analysis of land and water productivity reveal contrasting results at different scales. At tertiary and secondary scales, no correlation exists between distance from offtake and productivity. At the major unit (irrigation division), a moderate correlation is observed: 0.7 for land productivity, and 0.6 for water productivity. At the scheme scale, the correlation factors are somewhat lower for land productivity (0.4) and the same for water productivity (0.6). At the largest scale, the productivity appears to increase from head to tail divisions, suggesting potential overirrigation and waterlogging in the head parts leading to reduced productivity. Another possibility is the presence of better agricultural practices in the tail areas compared to the head.

Improving Water Efficiency Through Channel Lining - A Case Study of the Birinchiguri Runoff Irrigation Project in Assam, India

Water is the most essential commodity for human beings to be alive and so it is very necessary to make proper use of water without wasting it. Irrigation sector is the biggest consumer of water as more than 80% of available water resources in India is being presently utilized for irrigation purposes. However, the average water use efficiency of irrigation projects in the country is assessed to be only of the order of 30 to 35%. In the north eastern region also, performance of the existing irrigation schemes suffer from low water use efficiency due to distribution losses and poor operational maintenance and management and results in non - availability of water in the tail ends. Again, water demand for various purposes namely irrigation, drinking, domestic, power, industrial and other uses is increasing day by day leading to severe seasonal stress on water resources in the region. Its scarcity is more pronounced with increasing population and needs. In the present study, the water use efficiency of the Birinchiguri Flow Irrigation Project is determined as per methodology given in the guidelines for computing the Water Use Efficiency of the Irrigation Projects, Central Water Commission (CWC), February, 2014. It has also been attempted to analyze the scope of improvement of water use efficiency of the same.

Attitude of Onion Growers towards Drip Irrigation System in Tamil Nadu, India

The drip irrigation system is a kind of micro-irrigation system that has the potential to salvage the water and other nutrients by entrance water to drip gradually to the main roots if plants and other plant parts, which is from on the soil surface or buried inside the soil surface. The main aim of drip irrigation is to place water directly into the main root zone and decrease the water vapour. This study investigates the attitude of Onion growing farmers towards drip irrigation system. The survey was conducted to collect primary data from 119 onion growing farmers in Thondamuthur block of Coimbatore district. Findings reveal that less than three-fifths (57.14%) of the respondents expressed neutral attitude level towards drip irrigation system followed by 21.85 per cent had favourable and 21.01 per cent of the respondents had un-favourable attitude level towards drip irrigation system respectively. This study recommends the implementation of an extensive agricultural institution with more prevalent and periodic visits to drip owners should be established in order to provide regular technical advice and valuable data on the maintenance and repair of the drip irrigation scheme. Such initiatives could enhance the livelihood status of the onion growing farmers in Tamil Nadu.

Overall performance assessment of selected small-scale irrigation schemes using internal and external performance indicators in West Hararghe Zone, Eastern Ethiopia

This study was conducted to evaluate the overall performance of selected small-scale irrigation schemes using internal and external performance indicators. The performance of the irrigation schemes in relation to water balance was evaluated using three indicators. The results indicated that the relative water supply (RWS), relative irrigation supply (RIS), and field application ratio (FAR) of Midagdu irrigation scheme were 0.9, 1.3, and 0.75 respectively. This indicates that the water supply is not closely related to the water demand. However, for the Wadeti Irrigation scheme, the RWS, RIS, and FAR are 0.48, 0.35, and 2.83, respectively, indicating water stress. The Midagdu irrigation scheme shows 7496.75 birr/ha for both output per unit command area and output per unit cropped area. Output per unit irrigation water supply was 12.5 birr/m3, while output per unit water consumed was 4.4 birr/m3. For the Wadeti irrigation scheme, the values were 11,276.12 birr/ha, 11,276.12 birr/ha, 8.7 birr/m3, and 1.6 birr/m3, respectively. This study results showed that the Wadeti irrigation scheme is more land-efficient, while the Midagdu scheme is more water-efficient. The values of the hydraulic performance indicators Conveyance Efficiency (Ec), Water delivery capacity (WDC), and Delivery Performance Ratio (DPR), for the Midagdu irrigation scheme were 75 %, 0.45, and 0.8, respectively, while for the Wadeti irrigation scheme, the values were 42 %, 0.11, and 0.4, respectively. These results indicate that the water delivery performance of the two schemes was poor. Therefore, improving the hydraulic performance of the scheme requires minimizing water conveyance losses.

Performance Evaluation of Woybo Irrigation Scheme: Wolaita Zone, Southern Ethiopia

Performance evaluation of irrigation scheme is vital for realizing the present status and identifying the area for improvement. The study was conducted in Woybo irrigation scheme which is located in Boloso Sore district, Wolaita zone, Southern Ethiopia. This study was aimed to evaluate the performance of Woybo irrigation scheme with internal performance indicators. A total of nine demonstrating farmers' fields were selected from three canal reaches (head, middle, and tail) through purposive sampling. Primary and secondary data were collected, recorded, and analyzed. To measure the water applied to each experimental field, Parshall flume was installed, and soil samples were taken to determine soil texture, field capacity, permanent wilting point, and soil moisture content before and after each irrigation event at regular soil depth intervals. The results revealed that the mean conveyance efficiency was 60.85% and the application efficiency was 48.53%. Water distribution uniformity, deep percolation, and storage efficiencies were 84.56%, 51.47%, and 85.22%, respectively. However, the overall irrigation efficiency was found to be 29.53%, which was poorly performed due to inadequate water application, ineffective field water management, and low efficiency in water delivery systems. The main factors contributing to the poor water delivery performance included failures in water regulating gates, leakages, and siltation of canals. To address these problems, recommendations are made such as improvements in water application techniques should be implemented, through proper irrigation scheduling, water conservation practices, surge irrigation techniques, and providing extension support, training, and experience sharing. Additionally, maintenance and lining of earthen canals are necessary, along with the replacement and repair of leakages and broken water regulating and controlling structures. These measures can help to upgrade water delivery efficiency and improve the overall performance of the irrigation scheme.

Engineering geological investigation of Gololcha dam for evaluation of leakage and abutment slope stability, Eastern Ethiopia

The Ethiopian economy is primarily dependent on agriculture, making the construction of water harvesting facilities, such as dams, crucial for improving the productivity of this sector. The ongoing construction of the Gololcha dam on the Kurkura River located in Eastern Ethiopia aims to enhance irrigation schemes in the region. However, the dam site's complex geological and structural conditions pose challenges related to leakage and slope instability. Hence, this study focuses on addressing the abutment slope stability and leakage condition of this dam. This study employed kinematic analysis and the Limit Equilibrium Method (LEM) to assess slope stability. Additionally, engineering geological mapping, discontinuity surveys, seismic refraction tomography (SRT), and in-situ permeability testing were used to evaluate the leakage condition of the dam site. Notably, the permeability and SRT survey results identified potential leakage zones to the depth of 35, 30, and 35 m at the left, right, and central foundations of the dam, respectively. The kinematic method revealed one planar and two wedge modes of failure in the slope section covered by slightly weathered and fractured basalt rock at the right abutment. Further stability analysis of these two modes of failures via LEM analysis indicated slope instability under saturated conditions, emphasizing the role of pore water pressure. Furthermore, LEM modeling was directly utilized using the Slide 6.0 software to analyze the slope stability condition of the left abutment of the dam. This modeling also uncovered instability under saturated conditions. Based on the study findings, this study recommended curtain grouting to address potential leakage, as well as slope flattening and removing unstable rock wedges and loose material to stabilize unstable slope sections.

Projecting irrigation demand under IPCC climate change scenarios using WEAP modeling in the Rechna Doab, Pakistan

Pakistan is currently facing significant water scarcity issues, intensified by climate change. The main water source, the transboundary Indus River system, faces challenges such as water management, limited data availability, and inadequate management, leading to a gap between water demand and supply across various sectors. Agriculture, which consumes over 95 % of the country’s water resources, contributes nearly 25 % to the GDP, but is heavily dependent on irrigation due to limited rainfall. With rainfall meeting only 15 % of crop water requirements, groundwater plays a critical role, covering 40–60 % of irrigation needs. This study focuses on the Rechna Doab in the Indus Basin Irrigation System (IBIS) using the WEAP (Water Evaluation and Planning) model to assess the supply-demand gap under IPCC's climate change scenarios from Assessment Report Six (AR6). The main findings indicate: (1) Under SSP 8.5, unmet demand in the Upper Chenab Canal and other regions will increase by 33–47 % by mid-century; (2) demand site coverage will decline significantly, especially in Lower Gugera and Jhang branches; (3) groundwater dependency will increase substantially in response to the growing supply-demand gap. This work contributes to improving water management in Rechna Doab by providing a clear framework for adapting water resources to climate change using WEAP projections under various IPCC scenarios.

Using a Triple Sensor Collocation Approach to Evaluate Small-Holder Irrigation Scheme Performances in Northern Ethiopia

This study uses a triple-sensor collocation approach to evaluate the performance of small-holder irrigation schemes in the Zamra catchment of Northern Ethiopia. Crop water productivity (CWP), as an integrator of biomass production and water use, was used to compare the overall efficiencies of three types of irrigation systems: traditional and modern diversions, and dam-based irrigation water supply. Farmer-reported data often rely on observations, which can introduce human estimation and measurement errors. As a result, the evaluation of irrigation scheme performance has frequently been insufficient to fully explain crop water productivity. To overcome the challenges of using one single estimation method, we used a triple-sensor collocation approach to evaluate the efficiency of three small-scale irrigation schemes, using water productivity as an indicator. It employed three independent methods: remotely sensed data, a model-based approach, and farmer in-situ estimates to assess crop yields and water consumption. To implement the triple collocation appraisal, we first applied three independent evaluation methods, i.e., remotely sensed, model-based, and farmer in-situ estimates of crop yields and water consumption, to assess the crop water productivities of the systems. Triple-sensor collocation allows for the appraisal and comparison of estimation errors of measurement sensor systems, and enables the ranking of the estimators by their quality to represent the de-facto unknown true value, in our case: crop yields, water use, and its ratio CWP, in small-holder irrigated agriculture. The study entailed four main components: (1) collecting in-situ information and data from small-holder farmers on crop yields and water use; (2) derivation of remote sensing-based CWP from the FAO WaPOR open database and time series; (3) evaluation of biomass, crop yields and water use (evapotranspiration) using the AquaCrop model, integrating climate, soil data, and irrigation management practices; (4) performing and analysis of a categorical triple collocation analysis of the independent estimator data and performance ranking of the three sensing and small-holder irrigation systems. Maize and vegetables were used as main crops during three consecutive irrigation seasons (2017/18, 2018/19, 2019/20). Civil war prevented further field surveying, in-situ research, and data collection. The results indicate that remote sensing products are performed best in the modern and dam irrigation schemes for maize. For vegetables, AquaCrop performed best in the dam irrigation scheme.

Analyzing the impacts of climate change on ecosystem services provided by apple orchards in Southeast France using a process-based model

We know that fruit production, especially in the Mediterranean, will need to adapt to climate change to ensure the sustainability of fruit tree-based agroecosystems. However, there is a lack of evidence on the long-term effects of this change on sustainability indicators. To fill this gap, we used a fruit tree model, QualiTree, to analyze the impacts ofclimate change on the ecosystem services provided by apple orchards in south-eastern France. To do this, a blooming model was parameterized to simulate blooming date on the basis of climate data, and QualiTree was supplemented with a model of nitrogen processes in the tree and a soil module describing resource input (irrigation, mineral and organic fertilization), transfer in the soil (water and nitrogen) and metabolic transformation-immobilization (mineralization, (de)nitrification). This type of extension makes it possible to simulate a wide array of ecosystem services, including C sequestration, nitrate leaching and nitrous oxide emissions. The model was compared with data from an apple orchard in southeastern France. The predicted daily mean and variability over time of fruit growth, composition and soil water content were consistent with observed data. QualiTree was then used to assess the potential impacts of climate change on the ecosystem services supplied by apple orchards. For this purpose, weather variables from 2020 to 2100 were generated for three contrasted greenhouse gas emission scenarios, and simulations were performed under two irrigation schemes (no restriction and restricted use of water). Model outputs indicated that, on average, marketable apple yields would increase until 2050 and then subsequently decrease. The fruit refractometric index, an indicator of fruit quality, was projected to sharply decrease with the intensity of climate change. Ecosystem services such as C sequestration by the orchard will decrease with climate change severity, mainly due to a higher mineralization of soil humus, whereas N2O emissions will increase with larger denitrification rates. Soil water availability, fertility, drainage and leaching were predicted to depend more on the irrigation strategy than on climate change severity. The new functions performed in QualiTree broadened its predictive capabilities and allowed for a better understanding of ecosystem service delivery in fruit orchards under varying climate conditions.

Comprehensive Assessment of Climate Change Impacts on River Water Availability for Irrigation, Wheat Crop Area Coverage, and Irrigation Canal Hydraulic Capacity of Large-Scale Irrigation Scheme in Nepal

Comprehensive Assessment of Climate Change Impacts on River Water Availability for Irrigation, Wheat Crop Area Coverage, and Irrigation Canal Hydraulic Capacity of Large-Scale Irrigation Scheme in Nepal

Tailoring the surface energy balance algorithm for land-improved (SEBALI) model using high-resolution land/use land cover for monitoring actual evapotranspiration

Access to accurate near real-time actual evapotranspiration (ETa) data is crucial for monitoring and planning water uses, contributing to the sustainable management and development of water resources. However, ongoing ETa modeling efforts need to be improved when applied to small-sized farmlands in rugged landscapes like in the upper Blue Nile Basin. This study aimed to customize the Google Earth Engine-based Surface Energy Balance for the Algorithm Land–Improved (SEBALIGEE) model using high-resolution land use and land cover data. Additionally, the model, originally based on JavaScript, was updated to Python (SEBALIGEEpy), thereby enhancing its accessibility to a broader range of users and modelers. The ETa simulated with an updated version of the model was validated over croplands using publicly available AmeriFlux eddy covariance data. Furthermore, the SEBALIGEEpy-based ETa was evaluated over the Koga smallholder irrigation scheme in the Upper Blue Nile Basin, Ethiopia, by comparing it with the ETa obtained from the remote sensing-based Water Productivity Open-Access Portal (WaPOR) over seven seasons (2015/16–2022/23). The validation results show that the updated model provides more accurate ETa estimates with fewer missing records, with 9–11 % using the updated model compared to 14–29 % using the original SEBALIGEE model. The customized model has the potential to be used for agricultural water management in areas with fragmented land parcels like the Upper Blue Nile basin and beyond.

Gender differences in rice production participation among smallholder farmers in small-scale irrigation schemes in mbarali district, Tanzania

Smallholder farmers are crucial to agri-food production in sub-Saharan Africa. However, gender disparities in rice production participation persist in Tanzania. Existing research has yet to fully explore how demographic and socioeconomic factors influence gendered participation in rice production. This study assesses gender differences in rice production participation patterns among smallholder farmers and identify gender-related socio-economic and demographic factors influencing differences in participation within small-scale irrigation schemes in Mbarali District. Using cross-sectional approach, data were collected from 397 randomly selected farmers through structured questionnaire and analyzed with descriptive and inferential statistics, including ordered probit regression. The results revealed significant gender differences in rice production participation (p < 0.01). Male farmers had higher participation rates in activities such as land preparation, seedbed preparation, seedling management, irrigation, herbicide, fertilizer, pesticide application, harvesting, transporting, storage, and selling, while female farmers had higher participation rates in transplanting and weeding. The overall level of participation was moderate, with 78 % of male farmers and 49 % of female farmers. However, larger proportion of females (43 %) were at a lower participation levels compared to only 1 % of male farmers, while 21 % of males and 8 % of females were at high participation levels. Factors like household size, farming management, hierarchical position within households, decision-making power, and the ability to access irrigation water positively influenced participation levels, while land size cultivated had a negative impact (p < 0.05). These were gender-related socio-economic and demographic factors that disadvantage female farmers' participation (p < 0.05). While the age of the farmer and inadequacy of irrigation water significantly affected participation levels, farm-hired labour had positive influence, however, these factors were not gender-specific. The study concludes that gender differences in participation in rice production are influenced by demographic and socio-economic factors. To address these, the study recommends for interventions that reduce gender disparities by promoting equality in resource access, enhancing women's decision-making power over resources and ability to access irrigation water, and ensure sufficient water in small-scale irrigation schemes. The government should create an enabling environment that supporting female farmers in small-scale irrigation schemes for broader gender equality in agriculture and rural development.

Dynamics of knowledge creation and use for disaster management in Chokwe district, Mozambique

PurposeDisaster management practices depend on societies' knowledge. As climate change rapidly reshapes knowledge, questions arise about how knowledge for disaster management is produced and (re)shaped in modern world and how effective it is to withstand the ever-growing frequency and magnitude of disasters. This paper discusses the dynamics of knowledge creation and its use for disaster management in Chokwe district, southern Mozambique.Design/methodology/approachThe study reviews historical archives to identify how disaster management knowledge has changed from pre-colonization to the present.FindingsBefore colonization, local knowledge associated with traditions of asking gods and ancestors for rain and blessings in life prevailed. With colonization, around the 1500s, Portuguese rulers attempted to eliminate these local practices through an inflow of European settlers who disseminated scientific knowledge, built dams and irrigation schemes, which changed the region’s knowledge base and regimes of flooding and drought. After independence in 1975, the new government nationalized all the private property, expelled the settlers and imposed a socialist order. All knowledge on disaster management was dictated by the new government; those against this new order were sent to re-education centers implanted nationwide. Centralization of knowledge and power was, therefore, implanted. Socialism collapsed by the 1990s, and over time, there has been an amalgam of different knowledge bases and attempts to recognize local disaster management practices.Originality/valueThe Chokwe case shows that knowledge for disaster management evolves with local socioeconomic, political and environmental changes.

Effect of soil type on tipping point hydrological requirements for Axonopus compressus grass under extreme drought stress

Critical soil suctions (threshold, tipping point, and permanent wilting) corresponding to initial drought response, near-death stage, and complete mortality, respectively; is essential for formulating irrigation schemes of vegetation grown in compacted soil under drought conditions. The effect of soil types on these critical soil suctions are unexplored and is crucial in understanding the soil-specific plant water functions. This study aims to establish the drought response of Axonopus compressus (grass), based on stomatal conductance (gs) and chlorophyll fluorescence parameters (CI) grown in different soil types. A. compressus were grown in six soil types (2 coarse-grained and 4 fine-grained soils) for 8 weeks, followed by continued drought condition. The gs and CI were monitored along with soil suction and moisture content. Both leaf and root growth were observed to be higher in coarse-grained soils than fine-grained soils, even though the water retention of the coarse-grained soils were comparatively less. Drought stress initiation in plants was captured by ψthreshold from the CI (especially in fine-grained soils) before the gs response. The three critical soil suctions estimated from the correlation between CI and ψ were found to be increasing with higher soil clay fraction. Corresponding plant available water contents (based on v/v volumetric water content) with each of three critical soil suctions were found to be dependent on the relative growth of canopy to root growth that occurred in different soil medias. Especially, plant available water in ‘tipping suction’ was dependent on the soil clay fraction (i.e., higher fraction could restrict root water uptake) and is presented with a simple empirical correlation for A. compressus.

Responses of summer mesoscale convective systems to irrigation over the North China Plain based on convection-permitting model simulations

Extensive irrigation activities in the North China Plain (NCP) significantly influence regional weather and climate. However, previous studies focusing on the NCP were primarily based on coarse-resolution models, which are unable to explicitly resolve convection systems, causing large uncertainty in precipitation simulations. In this study, a convection-permitting model coupled with a dynamic irrigation scheme is utilized to investigate the impacts of irrigation on summertime mesoscale convective systems (MCSs) over the NCP. Sensitivity experiments with irrigation off and on are conducted for 5 summers and an MCS identification and tracking algorithm is applied to both satellite observations and model simulations. We find that incorporating irrigation in the model increases MCS precipitation, which agrees more with observations. The probability distributions of MCS lifetime, area, propagation speed, and intensity are all better simulated with irrigation. Irrigation increases the occurrence frequency of MCSs throughout the entire day. The nighttime increase is partly because of more frequent local initiation of MCS developed from isolated deep convection, while the daytime increase is mainly attributed to the changes in MCSs initiating elsewhere and then propagating to the NCP. On average, irrigation induces additional moisture that is more thermodynamically favorable for precipitation, but this effect is partially offset by the weakened ascending air motion primarily caused by irrigation surface cooling. Compared to weak MCS precipitation events, strong MCS precipitation events experience greater enhancement in precipitation intensity when including irrigation because the offset effect from the change in large-scale ascending air motion is insignificant. In addition, irrigation makes the variation of MCS precipitation intensity more correlated with the variation in ascending motion but less correlated with that in atmospheric moisture. Our results suggest the pronounced impacts of irrigation on MCSs over the NCP which should be included in numerical models to improve regional precipitation simulation and prediction.