The Temporal Variability of Rainfall and Streamflow into Lake Nakuru, Kenya, Assessed Using SWAT and Hydrometeorological Indices

Temporal variability analysis of rainfall and river discharges is useful in determining the likelihood of the occurrence of extreme events such as drought or flooding for the purposes of developing policies to mitigate their effects. This study investigated the temporal variability of rainfall and discharges into Lake Nakuru, Kenya using meteorological drought indicators and hydrological drought indicators from 1981 to 2018. The standardized precipitation index (SPI) and standardized precipitation evaporation index (SPEI) were used to characterize meteorological drought, while the streamflow drought index (SDI) was used to characterize hydrological drought. A SWAT model was applied for the prediction of streamflow on five tributaries of Lake Nakuru (Njoro, Ngosur, Nderit, Larmudiac, and Makalia Rivers). The model was successfully calibrated on Njoro River at the upstream of river gauging station 2FCO5 from 1984 to 1996, and the parameters were validated from 1997 to 2007. The SUFI-2 algorithm was applied in SWATCup to perform the calibration of the model. The model performance was considered satisfactory in daily time step (NSE = 0.58, R2 = 0.58 during calibration and NSE = 0.52, R2 = 0.68 during validation). The average annual water balance revealed that out of 823 mm received annual precipitation, 154 mm was surface runoff and 178 mm was the annual average water yield. The average annual actual evapotranspiration (ET) was 607 mm. The results for the temporal variation of the SPI and SDI for the five subcatchments indicated that the drought events identified by the 12-month SPI/SPEI were almost all identified by the 12-month SDI. At the catchment scale, SPI showed an equal distribution of wet and dry periods, with 50.00% of positive anomalies and 50.00% of negative anomalies being observed from 1981 to 2018, while SDI observes a high frequency of dry periods (52.63%) and a lower frequency of wet periods (47.37%). There is a higher frequency of wet periods compared to dry periods for both indices from 2009 to 2010 at 60.00% and 40.00% for SPI and 90.00% and 10.00% for SDI, respectively. Both indices observed that 1984 and 2000 were severely dry years (SPI/SPEI < −2.00), while 2018 was severely wet (SPI/SPEI > 2.00). The results for the variability in rainfall and streamflow indices revealed that the last 10 years (2009–2018) were wetter than the period from 1981 to 2008.

Download Full-text

Application of Meteorological and Hydrological Drought Indices to Establish Drought Classification Maps of the Ba River Basin in Vietnam

Hydrology ◽

10.3390/hydrology6020049 ◽

2019 ◽

Vol 6 (2) ◽

pp. 49 ◽

Cited By ~ 4

Author(s):

Doan Quang Tri ◽

Tran Tho Dat ◽

Dinh Duc Truong

Keyword(s):

River Basin ◽

Drought Index ◽

Assessment Tool ◽

Swat Model ◽

Standardized Precipitation Index ◽

Aridity Index ◽

Meteorological Drought ◽

Hydrological Drought ◽

Drought Indices ◽

Calibration And Validation

The objective of this study was to establish drought classification maps to simulate and calculate the lack of discharge in the Ba River basin in Vietnam. The maps were established using three meteorological drought indices (the Standardized Precipitation Index (SPI), the Drought Index (J), and the Ped Index (Ped)), the Soil and Water Assessment Tool (SWAT) model, and the hydrological drought index (KDrought). The results from the calculation of the SPI, Aridity Index (AI), and Ped at three stations (An Khe, Ayunpa, and MDrak) showed that the J index was suitable for the study area. Based on the J index, an extreme drought was predicted to occur at the Ayunpa, An Khe, and MDrak stations. During the calibration process, the SWAT Calibration Uncertainties Program (SWAT-CUP) model, with automatic algorithms, was used to select the parameters to optimize the SWAT model. For the calibration and validation, the observed discharge at two hydrology stations, An Khe and Cung Son, from the periods 1981–1991 and 1992–2002, respectively, were used. The simulated discharge was found to be acceptable, with the Nash–Sutcliffe efficiency (NSE), Percent bias (PBIAS), and R2 reaching good levels in both calibration and validation. The results from the calculation of the drought index (KDrought), and the established drought classification maps in 2016, showed that the most affected areas were the communes of the Gia Lai and Dak Lak provinces. The results from the simulation and calculations were found to be consistent with the situation that occurred in practice. The application of meteorological and hydrological drought indices, as well as the hydrological model, to support impact assessments of drought classification in space and time, as well as the establishment of forecasting and warning maps, will help managers to effectively plan policy responses to drought.

Download Full-text

The effect of climate type on timescales of drought propagation in an ensemble of global hydrological models

Hydrology and Earth System Sciences ◽

10.5194/hess-22-4649-2018 ◽

2018 ◽

Vol 22 (9) ◽

pp. 4649-4665 ◽

Cited By ~ 12

Author(s):

Anouk I. Gevaert ◽

Ted I. E. Veldkamp ◽

Philip J. Ward

Keyword(s):

Soil Moisture ◽

Land Surface ◽

Spatial Scales ◽

Standardized Precipitation Index ◽

Meteorological Drought ◽

Hydrological Drought ◽

Propagation Time ◽

Hydrological Models ◽

Land Surface Models ◽

Surface Models

Abstract. Drought is a natural hazard that occurs at many temporal and spatial scales and has severe environmental and socioeconomic impacts across the globe. The impacts of drought change as drought evolves from precipitation deficits to deficits in soil moisture or streamflow. Here, we quantified the time taken for drought to propagate from meteorological drought to soil moisture drought and from meteorological drought to hydrological drought. We did this by cross-correlating the Standardized Precipitation Index (SPI) against standardized indices (SIs) of soil moisture, runoff, and streamflow from an ensemble of global hydrological models (GHMs) forced by a consistent meteorological dataset. Drought propagation is strongly related to climate types, occurring at sub-seasonal timescales in tropical climates and at up to multi-annual timescales in continental and arid climates. Winter droughts are usually related to longer SPI accumulation periods than summer droughts, especially in continental and tropical savanna climates. The difference between the seasons is likely due to winter snow cover in the former and distinct wet and dry seasons in the latter. Model structure appears to play an important role in model variability, as drought propagation to soil moisture drought is slower in land surface models (LSMs) than in global hydrological models, but propagation to hydrological drought is faster in land surface models than in global hydrological models. The propagation time from SPI to hydrological drought in the models was evaluated against observed data at 127 in situ streamflow stations. On average, errors between observed and modeled drought propagation timescales are small and the model ensemble mean is preferred over the use of a single model. Nevertheless, there is ample opportunity for improvement as substantial differences in drought propagation are found at 10 % of the study sites. A better understanding and representation of drought propagation in models may help improve seasonal drought forecasting as well as constrain drought variability under future climate scenarios.

Download Full-text

Drought Propagation Patterns under Naturalized Condition Using Daily Hydrometeorological Data

Advances in Meteorology ◽

10.1155/2018/2469156 ◽

2018 ◽

Vol 2018 ◽

pp. 1-14 ◽

Cited By ~ 2

Author(s):

Jianzhu Li ◽

Yuangang Guo ◽

Yixuan Wang ◽

Shanlong Lu ◽

Xu Chen

Keyword(s):

Early Warning ◽

Assessment Tool ◽

Swat Model ◽

Meteorological Drought ◽

Threshold Level ◽

Hydrological Drought ◽

Propagation Pattern ◽

Drought Early Warning ◽

Hydrological Droughts

Drought propagation pattern forms a basis for establishing drought monitoring and early warning. Due to its regional disparity, it is necessary and significant to investigate the pattern of drought propagation in a specific region. With the objective of improving understanding of drought propagation pattern in the Luanhe River basin, we first simulated soil moisture and streamflow in naturalized situation on daily time scale by using the Soil and Water Assessment Tool (SWAT) model. The threshold level method was utilized in identifying drought events and drought characteristics. Compared with meteorological drought, the number of drought events was less and duration was longer for agricultural and hydrological droughts. The results showed that there were 3 types of drought propagation pattern: from meteorological drought to agricultural/hydrological drought (M-A/H), agricultural/hydrological drought without meteorological drought (NM-A/H), and meteorological drought only (M). To explain the drought propagation pattern, possible driven factors were determined, and the relations between agricultural/hydrological drought and the driven factors were built using multiple regression models with the coefficients of determination of 0.4 and 0.656, respectively. These results could provide valuable information for drought early warning and forecast.

Download Full-text

Finescale Evaluation of Drought in a Tropical Setting: Case Study in Sri Lanka

Journal of Applied Meteorology and Climatology ◽

10.1175/2008jamc1767.1 ◽

2009 ◽

Vol 48 (1) ◽

pp. 77-88 ◽

Cited By ~ 10

Author(s):

Bradfield Lyon ◽

Lareef Zubair ◽

Vidhura Ralapanawe ◽

Zeenas Yahiya

Keyword(s):

Sri Lanka ◽

Standardized Precipitation Index ◽

Meteorological Drought ◽

Drought Indices ◽

Drought Risk ◽

Mitigation And Adaptation ◽

Wide Range ◽

Drought Relief ◽

Drought Indicators ◽

The Standardized Precipitation Index

Abstract In regions of climatic heterogeneity, finescale assessment of drought risk is needed for policy making and drought management, mitigation, and adaptation. The relationship between drought relief payments (a proxy for drought risk) and meteorological drought indicators is examined through a retrospective analysis for Sri Lanka (1960–2000) based on records of district-level drought relief payments and a dense network of 284 rainfall stations. The standardized precipitation index and a percent-of-annual-average index for rainfall accumulated over 3, 6, 9, and 12 months were used, gridded to a spatial resolution of 10 km. An encouraging correspondence was identified between the spatial distribution of meteorological drought occurrence and historical drought relief payments at the district scale. Time series of drought indices averaged roughly over the four main climatic zones of Sri Lanka showed statistically significant (p < 0.01) relationships with the occurrence of drought relief. The 9-month cumulative drought index provided the strongest relationships overall, although 6- and 12-month indicators provided generally similar results. Some cases of appreciable drought without corresponding relief payments could be attributed to fiscal pressures, as during the 1970s. Statistically significant relationships between drought indicators and relief payments point to the potential utility of meteorological drought assessments for disaster risk management. In addition, the study provides an empirical approach to testing which meteorological drought indicators bear a statistically significant relationship to drought relief across a wide range of tropical climates.

Download Full-text

Analysing 21st century meteorological and hydrological drought events in Slovakia

Journal of Hydrology and Hydromechanics ◽

10.2478/johh-2018-0026 ◽

2018 ◽

Vol 66 (4) ◽

pp. 393-403 ◽

Cited By ~ 1

Author(s):

Miriam Fendeková ◽

Tobias Gauster ◽

Lívia Labudová ◽

Dana Vrablíková ◽

Zuzana Danáčová ◽

...

Keyword(s):

Water Balance ◽

Extreme Values ◽

Standardized Precipitation Index ◽

Meteorological Drought ◽

River Basins ◽

Hydrological Drought ◽

Water Balance Components ◽

Extreme Values Distribution ◽

The Standardized Precipitation Index ◽

The Relationship

Abstract Several quite severe droughts occurred in Europe in the 21st century; three of them (2003, 2012 and 2015) hit also Slovakia. The Standardized Precipitation Index (SPI) and Standardized Precipitation and Evapotranspiration Index (SPEI) were used for assessment of meteorological drought occurrence. The research was established on discharge time series representing twelve river basins in Slovakia within the period 1981–2015. Sequent Peak Algorithm method based on fixed threshold, three parametric Weibull and generalized extreme values distribution GEV, factor and multiple regression analyses were employed to evaluate occurrence and parameters of hydrological drought in 2003, 2011–2012 and 2015, and the relationship among the water balance components. Results showed that drought parameters in evaluated river basins of Slovakia differed in respective years, most of the basins suffered more by 2003 and 2012 drought than by the 2015 one. Water balance components analysis for the entire period 1931–2016 showed that because of continuously increasing air temperature and balance evapotranspiration there is a decrease of runoff in the Slovak territory.

Download Full-text

Calibration and validation of SWAT model and estimation of water balance components of Shaya mountainous watershed, Southeastern Ethiopia

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-10-13955-2013 ◽

2013 ◽

Vol 10 (11) ◽

pp. 13955-13978 ◽

Cited By ~ 21

Author(s):

A. A. Shawul ◽

T. Alamirew ◽

M. O. Dinka

Keyword(s):

Best Management Practices ◽

Management Practices ◽

Assessment Tool ◽

Swat Model ◽

Watershed Modeling ◽

Coefficient Of Determination ◽

Water Yield ◽

Time Step ◽

Monthly Streamflow ◽

Mountainous Watershed

Abstract. To utilize water resources in a sustainable manner, it is necessary to understand the quantity and quality in space and time. This study was initiated to evaluate the performance and applicability of the physically based Soil and Water Assessment Tool (SWAT) model in analyzing the influence of hydrologic parameters on the streamflow variability and estimation of monthly and seasonal water yield at the outlet of Shaya mountainous watershed. The calibrated SWAT model performed well for simulation of monthly streamflow. Statistical model performance measures, coefficient of determination (r2) of 0.71, the Nash–Sutcliffe simulation efficiency (ENS) of 0.71 and percent difference (D) of 3.69, for calibration and 0.76, 0.75 and 3.30, respectively for validation, indicated good performance of the model simulation on monthly time step. Mean monthly and annual water yield simulated with the calibrated model were found to be 25.8 mm and 309.0 mm, respectively. Overall, the model demonstrated good performance in capturing the patterns and trend of the observed flow series, which confirmed the appropriateness of the model for future scenario simulation. Therefore, SWAT model can be taken as a potential tool for simulation of the hydrology of unguaged watershed in mountainous areas, which behave hydro-meteorologically similar with Shaya watershed. Future studies on Shaya watershed modeling should address the issues related to water quality and evaluate best management practices.

Download Full-text

Evolution characteristics and relationship of meteorological and hydrological droughts from 1961 to 2018 in Hanjiang River Basin, China

Journal of Water and Climate Change ◽

10.2166/wcc.2021.267 ◽

2021 ◽

Author(s):

Lin Wang ◽

Jianyun Zhang ◽

Amgad Elmahdi ◽

Zhangkang Shu ◽

Yinghui Wu ◽

...

Keyword(s):

River Basin ◽

Human Activities ◽

Water Cycle ◽

Standardized Precipitation Index ◽

Meteorological Drought ◽

Hydrological Drought ◽

Evolution Characteristics ◽

Hanjiang River ◽

Hydrological Droughts ◽

Meteorological Droughts

Abstract In the context of global warming and increasing human activities, the acceleration of the water cycle will increase the risk of basin drought. In this study, to analyze the spatial and temporal evolution characteristics of hydrological and meteorological droughts over the Hanjiang River Basin (HRB); the Standardized Precipitation Index (SPI) and Standardized Runoff Index (SRI) were selected and applied for the period 1961–2018. In addition, the cross-wavelet method was used to discuss the relationship between hydrological drought and meteorological droughts. The results and analysis indicated that: (1) the meteorological drought in the HRB showed a complex cyclical change trend of flood-drought-flood from 1961 to 2018. The basin drought began to intensify from 1990s and eased in 2010s. The characteristics of drought evolution in various regions are different based on scale. (2) During the past 58 years, the hydrological drought in the HRB has shown a significant trend of intensification, particularly in autumn season. Also, the hydrological droughts had occurred frequently since the 1990s, and there were also regional differences in the evolution characteristics of drought in various regions. (3) Reservoir operation reduces the frequency of extreme hydrological drought events. The effect of reducing the duration and intensity of hydrological drought events by releasing water from the reservoir is most obvious at Huangjiagang Station, which is the nearest to Danjiangkou Reservoir. (4) The hydrological drought and meteorological drought in the HRB have the strongest correlation on the yearly scale. After 1990, severe human activities and climate change are not only reduced the correlation between hydrological drought and meteorological drought in the middle and lower reaches of the basin, but also reduced the lag time between them. Among them, the hydrological drought in the upper reaches of the basin lags behind the meteorological drought by 1 month, and the hydrological drought in the middle and lower reaches of the basin has changed from 2 months before 1990 to 1 month lagging after 1990.

Download Full-text

Impact of meteorological drought on hydrological drought in Toruń (central Poland) in the period of 1971–2015

Journal of Water and Land Development ◽

10.1515/jwld-2017-0001 ◽

2017 ◽

Vol 32 (1) ◽

pp. 3-12 ◽

Cited By ~ 6

Author(s):

Bogdan Bąk ◽

Katarzyna Kubiak-Wójcicka

Keyword(s):

Standardized Precipitation Index ◽

Meteorological Drought ◽

Middle Part ◽

Hydrological Drought ◽

External Factors ◽

Hydropower Plant ◽

Climate Factors ◽

Index Method ◽

Vistula River ◽

Groundwater Basin

Abstract The paper presents impact of meteorological drought on hydrological drought on the Vistula River in Toruń in the period of 1971-2015. It uses index method for the assessment of hydrological drought threat degree as a result of multi-month lasting meteorological drought. Based on the values of the SPI-24 (24-month standardized precipitation index) it was determined that meteorological drought in Toruń appeared six times and the total time of the phenomenon was 33% of the studied interval. Periods of hydrological drought on the Vistula River in Toruń have been determined based on the values of the SWI-24 (24-month standardized water level index). It has been found out that hydrological drought appeared four times and its total time was 10% longer that the meteorological drought. Based on the values of both indices (SPI-24 and SWI-24) correlation coefficient for months, seasons and years, it was found that the relation between both kind of droughts is weak (r < 0.5). That result is also confirmed in the distribution of both kinds of drought. Only in 32 months (8% of the total time) the intensity of the two simultaneously occurring drought was at least moderate. The achieved results revealed that the hydrological drought was occurring periodically, independent on meteorological drought. Hydrological drought was also influenced by the external factors (hydropower plant in Włocławek, Major Groundwater Basin - GZWP) and climate factors appearing in the upper and middle part of the river basin.

Download Full-text

Application of the Hidden Markov Bayesian Classifier and Propagation Concept for Probabilistic Assessment of Meteorological and Hydrological Droughts in South Korea

Atmosphere ◽

10.3390/atmos11091000 ◽

2020 ◽

Vol 11 (9) ◽

pp. 1000

Author(s):

Muhammad Nouman Sattar ◽

Muhammad Jehanzaib ◽

Ji Eun Kim ◽

Hyun-Han Kwon ◽

Tae-Woong Kim

Keyword(s):

Hydrological Cycle ◽

Standardized Precipitation Index ◽

Meteorological Drought ◽

Bayesian Classifier ◽

Hydrological Drought ◽

Data Availability ◽

Negative Effects ◽

The Standardized Precipitation Index ◽

Hydrological Droughts ◽

Drought Classes

Drought is one of the most destructive natural hazards and results in negative effects on the environment, agriculture, economics, and society. A meteorological drought originates from atmospheric components, while a hydrological drought is influenced by properties of the hydrological cycle and generally induced by a continuous meteorological drought. Several studies have attempted to explain the cross dependencies between meteorological and hydrological droughts. However, these previous studies did not consider the propagation of drought classes. Therefore, in this study, to consider the drought propagation concept and to probabilistically assess the meteorological and hydrological drought classes, characterized by the Standardized Precipitation Index (SPI) and Standardized Runoff Index (SRI), respectively, we employed the Markov Bayesian Classifier (MBC) model that combines the procedure of iteration of feature extraction, classification, and application for assessment of drought classes for both SPI and SRI. The classification results were compared using the observed SPI and SRI, as well as with previous findings, which demonstrated that the MBC was able to reasonably determine drought classes. The accuracy of the MBC model in predicting all the classes of meteorological drought varies from 36 to 76% and in predicting all the classes of hydrological drought varies from 33 to 70%. The advantage of the MBC-based classification is that it considers drought propagation, which is very useful for planning, monitoring, and mitigation of hydrological drought in areas having problems related to hydrological data availability.

Download Full-text

Comparison of Projection in Meteorological and Hydrological Droughts in the Cheongmicheon Watershed for RCP4.5 and SSP2-4.5

Sustainability ◽

10.3390/su13042066 ◽

2021 ◽

Vol 13 (4) ◽

pp. 2066

Author(s):

Jin Hyuck Kim ◽

Jang Hyun Sung ◽

Eun-Sung Chung ◽

Sang Ug Kim ◽

Minwoo Son ◽

...

Keyword(s):

General Circulation ◽

Drought Index ◽

Standardized Precipitation Index ◽

Coupled Model ◽

Meteorological Drought ◽

General Circulation Models ◽

Hydrological Drought ◽

Drought Indices ◽

Drought Period ◽

Drought Characteristics

Due to the recent appearance of shares socioeconomic pathway (SSP) scenarios, there have been many studies that compare the results between Coupled Model Intercomparison Project (CMIP)5 and CMIP6 general circulation models (GCMs). This study attempted to project future drought characteristics in the Cheongmicheon watershed using SSP2-4.5 of Australian Community Climate and Earth System Simulator-coupled model (ACCESS-CM2) in addition to Representative Concentration Pathway (RCP) 4.5 of ACCESS 1-3 of the same institute. The historical precipitation and temperature data of ACCESS-CM2 were generated better than those of ACCESS 1-3. Two meteorological drought indices, namely, Standardized Precipitation Index (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI) were used to project meteorological drought while a hydrological drought index, Standardized Streamflow Index (SDI), was used to project the hydrological drought characteristics. The metrological data of GCMs were bias-corrected using quantile mapping method and the streamflow was obtained using Soil and Water Assessment Tool (SWAT) and bias-corrected meteorological data. As a result, there were large differences of drought occurrences and severities between RCP4.5 and SSP2-4.5 for the values of SPI, SPEI, and SDI. The differences in the minimum values of drought index between near (2021–2060) and far futures (2061–2100) were very small in SSP2-4.5, while those in RCP4.5 were very large. In addition, the longest drought period from SDI was the largest because the variation in precipitation usually affects the streamflow with a lag. Therefore, it was concluded that it is important to consider both CMIP5 and CMIP6 GCMs in establishing the drought countermeasures for the future period.

Download Full-text