Hydro-meteorological Drought Research Articles

Assessment of Hydro-meteorological Drought Effects on Groundwater Resources in Hormozgan Region-South of Iran

Assessment of Hydro-meteorological Drought Effects on Groundwater Resources in Hormozgan Region-South of Iran

Integrated assessment for hydrometeorological drought based on Markov chain model

Drought assessment based on a single index cannot comprehensively reflect the characteristics of a drought affected by multiple factors. Therefore, the main purpose of this study is to accurately assess the drought by constructing an integrated drought assessment method (PDSI-SDI) that can combine the meteorological drought and hydrological drought at the same time. To better evaluate and forecast the drought, the Markov chain model is employed in this study to calculate the expected residence time, return period and transition probabilities of the drought. Furthermore, the Mann–Kendall method is adopted to predict the trend of the drought. The Weihe River Basin is selected as the study area, and according to the distribution characteristics of the water system, it is divided into five districts in order to better assess the drought. Results indicate that: (1) spatially, drought probabilities increase from south to north and west to east. (2) Temporally, probabilities of spring droughts are the highest, followed by summer droughts and autumn droughts, winter droughts have the lowest probabilities, extreme droughts are more likely to occur in autumn. (3) Drought preferentially transfers within the same scenario, except scenario 4 (meteorological drought with no hydrological drought) in autumn is prone to shift to scenario 1 (no meteorological drought with no hydrological drought). (4) There is a significant drying trend of the drought in the Weihe River Basin at the significance level of 95 %. The integrated drought assessment method and other methods adopted in this study can be applied in other regions as well.

Hydro-Meteorological Drought Projections into the 21-st Century for Selected Polish Catchments

The nature of drought conditions is estimated using a range of indices describing different aspects of drought events. Three drought indices are evaluated, namely the Standardized Precipitation Index (SPI), Standardized Precipitation Evapotranspiration Index (SPEI) and Standardized Runoff Index (SRI), using observed hydroclimatic data and applying them to hydro-meteorological projections into the 21st century. The first two indices are evaluated using only meteorological variables and from this point of view, are better suited to meteorological drought projections than the third index, SRI, which is based on catchment discharge and represents hydrological drought. We assess information contained in those indices and their suitability to catchment scale climate projection drought assessment in ten selected Polish catchments, representing different hydro-climatic conditions, which are used as a case study. Projections of climatic variables (precipitation and temperature) are obtained from the EURO-CORDEX initiative derived from seven climate models at a grid resolution of 12.5 km for the time period 1971–2100. Future runoff projections for the catchments are obtained using a conceptual rainfall-runoff model (HBV). The results of analyses of indices based on observations in the reference period show consistent estimates for most of the catchments. Hydro-meteorological climate model projections for three periods, including the reference period 1971–2000, and two 30-year periods, near-future 2021–2050 and far-future 2071–2100, are used to estimate changes of future drought conditions in the catchments studied. The results show a substantial variation of temporal drought patterns over the catchments and their dependence on projected precipitation and temperature variables and the type of indices applied. Of the three indices studied, only SPEI projections indicate drier conditions in the catchments in the far-future period. The other two indices, SPI and SRI, indicate wetter climates in the future.

Hydro-Meteorological Drought Assessment Based on Aggregate Drought Index (ADI) and its prediction with Markov Chain in Sarbaz River Basin (Southeast of Iran)

Hydro-Meteorological Drought Assessment Based on Aggregate Drought Index (ADI) and its prediction with Markov Chain in Sarbaz River Basin (Southeast of Iran)

Exploring hydro-meteorological drought patterns over the Greater Horn of Africa (1979–2014) using remote sensing and reanalysis products

Spatio-temporal patterns of hydrological droughts over the Greater Horn of Africa (GHA) are explored based on total water storage (TWS) changes derived from time-variable gravity field solutions of Gravity Recovery And Climate Experiment (GRACE, 2002–2014), together with those simulated by Modern Retrospective Analysis for Research Application (MERRA, 1980–2014). These hydrological extremes are then related to meteorological drought events estimated from observed monthly precipitation products of Global Precipitation Climatology Center (GPCC, 1979–2010) and Tropical Rainfall Measuring Mission (TRMM, 1998–2014). The major focus of this contribution lies on the application of spatial Independent Component Analysis (sICA) to extract distinguished regions with similar rainfall and TWS with similar overall trend and seasonality. Rainfall and TWS are used to estimate Standard Precipitation Indices (SPIs) and Total Storage Deficit Indices (TSDIs), respectively that are employed to characterize frequency and intensity of hydro-meteorological droughts over GHA. Significant positive (negative) changes in monthly rainfall over Ethiopia (Sudan) between 2002 and 2010 leading to a significant increase in TWS over the central GHA region were noted in both MERRA and GRACE TWS (2002–2014). However, these trends were completely reversed in the long-term (1980–2010) records of rainfall (GPCC) and TWS (MERRA). The four independent hydrological sub-regions extracted based on the sICA (i.e., Lake Victoria Basin, Ethiopia-Sudanese border, South Sudan, and Tanzania) indicated fairly distinct temporal patterns that matched reasonably well between precipitation and TWS changes. While meteorological droughts were found to be consistent with most previous studies in all sub-regions, their impacts are clearly observed in the TWS changes resulting in multiple years of extreme hydrological droughts. Correlations between SPI and TSDI were found to be significant over Lake Victoria Basin, South Sudan, and Tanzania. The low correlations between SPI and TSDI over Ethiopia are likely related to inconsistency between TWS and precipitation signals. Further, we found that hydrological droughts in these regions were significantly associated with Indian Ocean Dipole (IOD) events while El Niño Southern Oscillation (ENSO) plays a secondary role.

Transitional variations and risk of hydro-meteorological droughts in the Tarim River basin, China

The Tarim River basin, China, is a typical arid inland river basin in China. Management of water resources and agricultural development rely heavily on the understanding of droughts. In this study, an integrated drought index is proposed, based on the Standardized Precipitation Evapotranspiration Index and the Standardized Runoff Index, and then the changing properties of drought regimes have been analyzed using a Markov Chain model. Results indicate that: (1) the Kaidu and Aksu Rivers are dominated by prompt transition between hydrological and meteorological droughts. Long-lasting droughts heavily impact agricultural development in the Kaidu and Yarkand River basins; (2) the Kaidu and Aksu River basins are influenced mainly by hydro-meteorological droughts and hydrological drought is dominant in the Yarkand River basin; (3) different drought conditions are the results of different sources of river runoff. Increasing precipitation alleviate droughts in the Tarim River basin. However, a drying tendency can still be found in the Kaidu River basin; (4) higher probability is detected for the transition from both meteorological and hydrological wet to both meteorological and hydrological dry, implying that the Tarim River basin is sensitive to both meteorological and hydrological droughts. Results of this study are of practical value for the regional management of water resources, planning of agricultural irrigation, and measures for mitigation of hydrological and meteorological droughts.

Persistence of Hydrometeorological Droughts in the United Kingdom: A Regional Analysis of Multi-Season Rainfall and River Flow Anomalies

This paper investigates the spatial and temporal properties of persistent meteorological and hydrological droughts in the UK at national to sub-regional scales. Using 1961–1990 as the reference period, it is shown that the longest observed run of below average rainfall since the 1870s persisted for four years in northern England and parts of Scotland during 1892–1896. The longest observed run of below average discharge since the 1950s/1960s was found for some groundwater fed rivers in the English lowlands and lasted up to 5.5 years during 1988–1993. Distributions of dry-spell lengths were represented by a Markov model fit to each rainfall and discharge record. This model provides a good fit to observed geometric distributions of spell lengths and provides credible runs of below average river flows lasting up to a decade in some vulnerable catchments in southern England. Droughts of this persistence may not yet have occurred within the instrumented record but could have profound water management implications for the region. Predicted 100-year drought durations for catchments in northern England may not be as long but could have serious ramifications for surface water supplies. These findings point to a risk of irreversible drought impacts on aquatic communities that are simultaneously stressed by unsustainable abstractions, poor water quality and/or habitat modifications.

Ensemble Climate Projection for Hydro-Meteorological Drought over a river basin in Central Highland, Vietnam

This study focuses on the Hydro-Meteorological Drought assessments by Ensemble Climate Projections from a regional climate model (Weather Research and Forecasting, WRF) that downscaled 3 Global Climate Models under a baseline period (1961–1990) and under a future scenario A2 for 2071–2100. The Meteorological Drought is assessed using the Standardized Precipitation Index (SPI) while the Hydrological Drought is analyzed by using both the semi-distributed hydrology model SWAT and Standardized Runoff Index (SRI). The catchment under study is a small river basin lying on the Central Highland area of Vietnam. This area is the source for perennial plantation which produces most of the coffee for Vietnam making it the world’s second most exporter of coffee next to Brazil. Additionally, this region is also one of the important sources for hydropower of Vietnam and one of the main tributaries for the Mekong river at the downstream. This region has been known prone to drought, especially during dry seasons of March and April. Therefore, simulating drought for this area is significant to study the water supply and water balance for the region for future planning and adaptation.

The impact of climate change on hydrometeorological droughts at a basin scale

Summary Three Global Climate Models (GCMs) output (precipitation and temperature), bias corrected with the WATCH Forcing Data (WFD), for the A2 and B1 scenarios, are used for drought assessment at a basin scale. At a first step, the hydrological model IHMS-HBV was calibrated using both local and large scale forcing data (precipitation and temperature) aiming to assess the suitability of large scale forcing data in a small basin, Platis, located in Crete, for the period 1974–1999. The second step includes the forcing of the WFD calibrated HBV model with the bias corrected GCM output from 2001 to 2100 (WATCH Driving Data). The produced hydrological variables, flow, soil moisture and lower groundwater reservoir volume were used for the hydrological regime assessment and drought identification with the aid of the threshold level method. A quantitative comparison with four future sub-periods was carried out addressing the drought events number, duration and deficit volume. Simulations of both emission scenarios indicate a significant decrease in all hydrological parameters. The relative change of drought characteristics for the future periods in terms of the three-model ensemble implied severe drought conditions. For A2 scenario, it was found that the number of drought events could increase up to 98%, 109% and 81% in flow, soil moisture and groundwater respectively. B1 scenario provided more conservative estimates, with an increase of drought events number up to 56%, 92% and 34% in flow, soil moisture and groundwater, respectively. The drought duration difference between scenarios reaches up to 33%, 89% and 34% for simulated flow, soil moisture and groundwater respectively till 2100. Moderate changes can be noticed in drought deficit volume with an estimated maximum increase of 19%, 33% and 22% in flow, soil moisture and groundwater involving A2 scenario, whereas B1 scenario projected 10%, 2% and 26% maximum increase for the former parameters. The evolution of the hydrological parameters is in line with the projected decreasing precipitation and increasing temperature trends.

Assessment of remotely sensed drought features in vulnerable agriculture

Abstract. The growing number and effectiveness of Earth observation satellite systems, along with the increasing reliability of remote sensing methodologies and techniques, present a wide range of new capabilities in monitoring and assessing droughts. A number of drought indices have been developed based on NOAA-AVHRR data exploiting the remote sensing potential at different temporal scales. In this paper, the remotely sensed Reconnaissance Drought Index (RDI) is employed for the quantification of drought. RDI enables the assessment of hydro-meteorological drought, since it uses hydrometeorological parameters, such as precipitation and potential evapotranspiration. The study area is Thessaly, central Greece, which is a drought-prone agricultural region characterized by vulnerable agriculture. Several drought features are analyzed and assessed by using monthly RDI images over the period 1981–2001: severity, areal extent, duration, periodicity, onset and end time. The results show an increase in the areal extent during each drought episode and that droughts are classified into two classes, namely small areal extent drought and large areal extent drought, respectively, lasting 12 or 13 months coinciding closely with the hydrological year. The onset of large droughts coincides with the beginning of the hydrological year, whereas the onset of small droughts is in spring. During each drought episode, the maximum occurs usually in the summer and they all last until the end of the hydrological year. This finding could justify an empirical prognostic potential of drought assessment.

Geoinformatic Intelligence Methodologies for Drought Spatiotemporal Variability in Greece

One of the most important hazards in terms of cost, frequency of occurrence and impact on humans is drought. Drought indices are estimations of precipitation shortage and water supply deficit. Satellite drought indices are normally radiometric recordings of vegetation condition and dynamics, exploiting the unique spectral signatures of canopy elements, particularly in the red and near-infrared bands. However, the identification of drought based on the Reconnaissance Drought Index (RDI) enables the assessment of hydro-meteorological drought, since it uses hydro-meteorological parameters. RDI is a fairly comprehensive index as it combines the simplicity of use and the successfully assessment and monitoring of the phenomenon. However, the study and understanding of the spatiotemporal variability of drought is not an easy process. In this study the main goal is to use the PCA + clustering method to transform the RDI temporal data (1982–2001) and cluster the different regions of Greece based on that temporal variations. Firstly, Principal Component Analysis (PCA) applied onto 19 annual RDI indices followed by Clustering that was based on certain eigenchannels resulted from the previous PCA analysis. Both methods are linear transformations capable to decorrelate the spatiotemporal information provided in the estimated RDI. The time series presented approach proved to be advantageous in relation to other statistical methods used to describe variability and provide excellent and fast results for stakeholders and environmental organizations. The results are quite satisfactory in classifying the drought-induced climatic regions of Greece.