scholarly journals Improvement of Hargreaves–Samani Reference Evapotranspiration Estimates with Local Calibration

Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2272 ◽  
Author(s):  
Daniel Althoff ◽  
Robson Argolo dos Santos ◽  
Helizani Couto Bazame ◽  
Fernando França da Cunha ◽  
Roberto Filgueiras
Keyword(s):  
Reference Evapotranspiration ◽  
Eastern Region ◽  
Local Calibration ◽  
Middle Portion ◽  
Wet Season ◽  
Water Shortages ◽  
Simple Method ◽  
Irrigation Water Management ◽  
Single Calibration ◽  
Separate Calibration

Improving irrigation water management is an important asset when facing increased water shortages. The Hargreaves–Samani (HS) method is a simple method that can be used as an alternative to the Penman–Monteith (PM) method, which requires only temperature measurements for estimating reference evapotranspiration (ETo). However, the applicability of this method relies on its calibration to local meteorological specificities. The objective of this study was to investigate the effects of local calibration on the performance of the HS equation. The study was carried out for the middle portion of the São Francisco River Basin (MSFB), Brazil, and considered four calibration approaches: A1—single calibration for the entire MSFB; A2—separate calibration by clusters of months; A3—by clusters of stations; and A4—for all contexts resulting by combining A2 and A3. Months from the wet season showed larger improvements by the calibration of the HS model, since mean air temperature and its daily range showed stronger correlations to ETo. On the other hand, the months from the dry season and stations from the eastern region of MSFB performed poorly regardless of the calibration approach adopted. This occurred because, in those cases, ETo presented larger correlation to variables that are missing in the HS equation, and the use of the full PM equation seems unavoidable.

scholarly journals Examining the Value of Global Seasonal Reference Evapotranspiration Forecasts to Support FEWS NET’s Food Insecurity Outlooks

2017 ◽  
Vol 56 (11) ◽  
pp. 2941-2949 ◽  
Author(s):  
Shraddhanand Shukla ◽  
Daniel McEvoy ◽  
Mike Hobbins ◽  
Greg Husak ◽  
Justin Huntington ◽  
...  
Keyword(s):  
Food Insecurity ◽  
Central Asia ◽  
East Africa ◽  
Central America ◽  
Southern Africa ◽  
Early Warning ◽  
Reference Evapotranspiration ◽  
Dry Season ◽  
Wet Season ◽  
Skill Evaluation

AbstractThe Famine Early Warning Systems Network (FEWS NET) team provides food insecurity outlooks for several developing countries in Africa, central Asia, and Central America. This study describes development of a new global reference evapotranspiration (ET0) seasonal reforecast and skill evaluation with a particular emphasis on the potential use of this dataset by FEWS NET to support food insecurity early warning. The ET0 reforecasts span the 1982–2009 period and are calculated following the American Society for Civil Engineers formulation of the Penman–Monteith method driven by seasonal climate forecasts of monthly mean temperature, humidity, wind speed, and solar radiation from the National Centers for Environmental Prediction CFSv2 model and the National Aeronautics and Space Administration GEOS-5 model. The skill evaluation, using deterministic and probabilistic scores, focuses on the December–February (DJF), March–May (MAM), June–August (JJA), and September–November seasons. The results indicate that ET0 forecasts are a promising tool for early warning of drought and food insecurity. Globally, the regions where forecasts are most skillful (correlation > 0.35 at leads of 2 months) include the western United States, northern parts of South America, parts of the Sahel region, and southern Africa. The FEWS NET regions where forecasts are most skillful (correlation > 0.35 at lead 3) include northern sub-Saharan Africa (DJF; dry season), Central America (DJF; dry season), parts of East Africa (JJA; wet season), southern Africa (JJA; dry season), and central Asia (MAM; wet season). A case study over parts of East Africa for the JJA season shows that ET0 forecasts in combination with the precipitation forecasts would have provided early warning of recent severe drought events (e.g., in 2002, 2004, 2009) that contributed to substantial food insecurity in the region.

scholarly journals How might climate change affect river flows across West Africa?

2021 ◽  
Vol 169 (3-4) ◽  
Author(s):  
Ponnambalam Rameshwaran ◽  
Victoria A. Bell ◽  
Helen N. Davies ◽  
Alison L. Kay
Keyword(s):  
Climate Change ◽  
West Africa ◽  
Regional Scale ◽  
Weather Data ◽  
Eastern Region ◽  
Water Shortages ◽  
River Flows ◽  
Considerable Uncertainty ◽  
Modelling Framework ◽  
The Impact

AbstractWest Africa and its semi-arid Sahelian region are one of the world’s most vulnerable regions to climate change with a history of extreme climate variability. There is still considerable uncertainty as to how projected climate change will affect precipitation at local and regional scales and the consequent impact on river flows and water resources across West Africa. Here, we aim to address this uncertainty by configuring a regional-scale hydrological model to West Africa. The model (hydrological modelling framework for West Africa—HMF-WA) simulates spatially consistent river flows on a 0.1° × 0.1° grid (approximately 10 km × 10 km) continuously across the whole domain and includes estimates of anthropogenic water use, wetland inundation, and local hydrological features such as endorheic regions. Regional-scale hydrological simulations driven by observed weather data are assessed against observed flows before undertaking an analysis of the impact of projected future climate scenarios from the CMIP5 on river flows up to the end of the twenty-first century. The results indicate that projected future changes in river flows are highly spatially variable across West Africa, particularly across the Sahelian region where the predicted changes are more pronounced. The study shows that median peak flows are projected to decrease by 23% in the west (e.g. Senegal) and increase by 80% in the eastern region (e.g. Chad) by the 2050s. The projected reductions in river flows in western Sahel lead to future droughts and water shortages more likely, while in the eastern Sahel, projected increases lead to future frequent floods.

Residual Mass Severity Index (RMSI) – a duration free method to characterise droughts

2020 ◽  
Author(s):  
Rounak Afroz ◽  
Ashish Sharma ◽  
Fiona Johnson
Keyword(s):  
Climate Change ◽  
General Circulation ◽  
Severity Index ◽  
General Circulation Models ◽  
Drought Indices ◽  
Severe Drought ◽  
Monthly Precipitation ◽  
Water Shortages ◽  
Simple Method ◽  
Residual Mass

<p>The complexity of representing droughts has led to many drought indices being developed. A common aspect for many of these indices, however, is the need to adopt a predefined time period, over which a drought is characterized. Therefore, to declare a catchment as drought-impacted, 6, 12 or 24-month SPI are required. Actual water allocations, however, are required at all times and are thus duration free; a concept well described by the well-known residual mass curve. Here we propose a new framework to characterize drought, termed as the Residual Mass Severity Index (RMSI). As the name suggests, the RMSI defines drought based on the magnitude of the residual mass in any location which is calculated by performing a water balance using a prescribed demand. Demand here is adopted as the median monthly precipitation for the region. Water shortages only become significant when there is a sustained deficit compared to this demand. The above described residual mass is standardized to formulate the RMSI across Australia. The new RMSI has been validated against established drought indices (such as the SPI) to highlight the advantages of a duration-free drought index.</p><p>RMSI provides a simple method of assessing sustained and severe drought anomalies which is important with expected increases in water scarcity due to anthropogenic climate change. We demonstrate that RMSI can be used as a tool to evaluate the performance of General Circulation Models (GMCs) in representing the sustainability of water resource systems as a product of resilience, reliability, and vulnerability (RRV) of the system. Future projections of drought from GCMs which perform well in representing RMSI in the RRV context in the historical climate are then compared to drought projections from the full CMIP5 ensemble.</p><p>Keywords: Drought, Residual Mass Curve, SPI, RRV, Climate Change, CMIP5 GCMs</p>

scholarly journals Preventive strategy in response to climate change and infrastructural failures for Jakarta slum dwellers

2012 ◽  
Vol 5 (1) ◽  
pp. 421-434
Author(s):  
V. Pooroe ◽  
I. Prabaharyaka
Keyword(s):  
Climate Change ◽  
Water Supply ◽  
Urban Poor ◽  
Storage System ◽  
Preventive Strategy ◽  
Wet Season ◽  
Water Shortages ◽  
Community Based ◽  
Water Users ◽  
Annual Water

<p><strong>Abstract.</strong> Jakarta is a city with unpredictable yet annual water shortages, both during the dry and wet season, which disproportionately affect the urban poor. One possible solution is to redevelop the existing water supply system which is now working in one of the largest slum area in Penjaringan, North Jakarta. This system is equipped with a large meter, the Master Meter, to record the communal water consumption and individual meters to record household consumptions. The Community Based Organization uses, operates, and maintains the system based on agreement with water users. Improvement of the Master Meter is achieved by harvesting uncollected rain water during the wet season with its high rainfall intensity, modifying the water storage system and improving the influent water quality. This paper aims to provide a preventive strategy in response to climate change and infrastructural failures based on a case study of community-based water supply project in Penjaringan, Jakarta.</p>

scholarly journals Reviving the "Ganges Water Machine": where and how much?

2015 ◽  
Vol 12 (9) ◽  
pp. 9741-9763 ◽  
Author(s):  
L. Muthuwatta ◽  
U. A. Amarasinghe ◽  
A. Sood ◽  
S. Lagudu
Keyword(s):  
Water Availability ◽  
Water Demand ◽  
Surface Runoff ◽  
Assessment Tool ◽  
The State ◽  
Ganges River ◽  
Wet Season ◽  
Water Shortages ◽  
Bihar State ◽  
The Ganges

Abstract. Surface runoff generated in the monsoon months in the upstream parts of the Ganges River Basin contributes substantially to downstream floods, while water shortages in the dry months affect agricultural production in the basin. This paper examines the parts (sub-basins) of the Ganges that have the potential for augmenting subsurface storage (SSS), increase the availability of water for agriculture and other uses, and mitigate the floods in the downstream areas. The Soil and Water Assessment Tool (SWAT) is used to estimate sub-basin-wise water availability. The water availability estimated is then compared with the sub-basin-wise un-met water demand for agriculture. Hydrological analyses revealed that five sub-basins produced more than 10 billion cubic meters (B m3) of annual surface runoff consistently during the simulation period. In these sub-basins, less than 50 % of the annual surface runoff is sufficient to irrigate all irrigable land in both the \\textit{Rabi} (November to March) and summer (April to May) seasons. Further, for most of the sub-basins, there is sufficient water to meet the un-met water demand, provided that it is possible to capture the surface runoff during the wet season. It is estimated that the average flow to Bihar State from the upstream of the Ganges, a downstream basin location, is 277 ± 121 B m3, which is more than double the rainfall in the state alone. Strong relationships between outflows from the upstream sub-basins and the inflows to Bihar State suggested that flood inundation in the state could be reduced by capturing a portion of the upstream flows during the peak runoff periods.

scholarly journals Distribution of antibiotics in the vadose zone in Xiaodian Sewage Irrigation Area, Northern China

2019 ◽  
Vol 98 ◽  
pp. 09016
Author(s):  
Jiale Li ◽  
Yihui Dong ◽  
Zhanxue Sun ◽  
Huijun Ding
Keyword(s):  
Vadose Zone ◽  
Soil Profile ◽  
Flow Direction ◽  
Northern China ◽  
Sewage Sample ◽  
Sewage Irrigation ◽  
Lateral Migration ◽  
Wet Season ◽  
Water Shortages ◽  
Irrigation Area

Because of water shortages, the Xiaodian area in northern China had a long history of sewage irrigation. To study the distribution of antibiotics in the vadose zone, a sewage sample and 5 soil profiles were collected and analyzed. Macrolides and Fluoroquinolones were the main antibiotics observed in the shallow vadose zone. The contents of antibiotics in the soil profile nearby the sewage irrigation area were 2-3 times greater than in the groundwater irrigation area, indicating that sewage irrigation has had a significant impact on the contents of antibiotics in the soil. The elevation of antibiotic contents during the wet season is likely related to the fluctuating water level within the shallow vadose zone. The distribution of antibiotics is influenced by the flow direction of irrigation water. Moreover, the possibility of introducing antibiotics into the soil of the shallow vadose via the lateral recharge of sewage in the Beizhang Drainage Canal can not be excluded. Approximately 50 % of Fluoroquinolones were reduced in the upper 50 cm of the soil zone and 70 % at 80 cm depth. Tetracyclines may have experienced significant lateral migration. Macrolides and Sulfonamides (SMs) have similar soil profile distributions, with a concentration decrease down to 20 cm depth.

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