Identifying Water Storage Variation in Krishna Basin,India from <Emphasis Type="Italic">in situ</Emphasis> and Satellite based Hydrological Data

Terrestrial water storage (TWS), a sum total of water stored on or beneath the earth’s surface, transits in response to hydroclimatic processes such as precipitation, evapo-transpiration, runoff etc. and serves an indicator of hydrological condition of a region. We analyse spatio-temporal variance of water storage in Krishna Basin, India, derived from in-situ groundwater data and Gravity Recovery and Climate Experiment (GRACE) satellite data in order to determine physical causes of variations, and compare the variance with climatic factors such as Cumulative Rainfall Departure (CRD) and drought index i.e. Standardized Precipitation Index (SPI). GRACE satellite based TWS is found to reflect insitu groundwater changes and also shows a relationship with drought patterns as indicated by a good correlation with SPI. The largest part of TWS represents seasonal flux, and at an interannual scale, TWS depicts spatio-temporal variability in response to drought index viz. SPI. We infer that the groundwater storage derived from GRACE time-variable gravity solutions can be utilised to complement in-situ observations at basin scale and it reflects climatic forcing quite well.     

Late Quaternary behavior of the East African monsoon and the importance of the Congo Air Boundary

Both Atlantic and Indian Ocean climate dynamics exert influence over tropical African hydroclimate, producing complex patterns of convergence and precipitation. To isolate the Indian Ocean influence on African paleohydrology, we analyzed the deuterium/hydrogen ratio of higher plant leaf waxes (δD_wax) in a 25 000-year sediment record from Lake Challa (3° S, 38° E) in the easternmost area of the African tropics. Whereas both the seismic record of inferred lake level fluctuations and the Branched and Isoprenoidal Tetraether (BIT) index proxy record changes in hydrology within the Challa basin, δD_wax, as a proxy for the isotopic composition of precipitation (δD_P) is interpreted as a tracer of large-scale atmospheric circulation that integrates the history of the moisture transported to the Lake Challa area. Specifically, based on modern-day isotope–rainfall relationships, we argue that Lake Challa δD_wax reflects the intensity of East African monsoon circulation. The three hydrological proxy records show generally similar trends for the last 25 000 years, but there are important differences between them, primarily during the middle Holocene. We interpret this deviation of δD_wax from local hydrological history as a decoupling of East African monsoon intensity – which heavily influences the isotopes of precipitation in East Africa today – from rainfall amount in the Challa basin. In combination, the hydrological proxy data from Lake Challa singularly highlight zonal gradients in tropical African climate that occur over a variety of timescales, suggesting that the Congo Air Boundary plays a fundamental role in controlling hydroclimate in the African tropics.     

遥感反演2000—2020年青藏高原水储量变化及其驱动机制

气候变化对青藏高原的水储量造成显著影响,严重威胁下游地区涉及10亿人口的水资源安全、水灾害防治和水生态保护。本研究集成多源卫星遥感(包括卫星重力、卫星测高、光学影像等)及相关反演融合算法和部分再分析数据,在前期工作基础上延长并生成了2000—2020年青藏高原各类水储量(湖泊、冰川、雪深和雪水当量、总水储量)变化数据,并分析其气候驱动机制。结果表明：(1) 2002—2020年间青藏高原外流区总水储量呈显著下降趋势(-10.90 Gt/a),主要由冰川质量损失主导;内流区总水储量呈显著上升趋势(6.40 Gt/a),其中湖泊水量扩张占主导。(2)青藏湖泊整体呈扩张趋势,并分为3个阶段：2000—2012年为平稳增长期(6.35 Gt/a),2012—2017年为相对稳定期(1.42 Gt/a),2017年后进入快速增长期(10.59 Gt/a);湖泊水量变化与降水量变化一致性较高。(3)藏东南地区的冰川呈快速消融趋势(-4.50 Gt/a),气温升高和降水年际波动是近年来该地区冰川后退的主要原因。(4) 2016—2020年平均雪水当量较2001—2015年呈增加趋势,积雪变化主要受累...     

Estimation of regional evapotranspiration in the extended Salado Basin (Argentina) from satellite gravity measurements

In this study, regional evapotranspiration is estimated in a wide flatland area that includes Salado River Basin and four tributary basins by using gravity measurements of the space mission Gravity Recovery and Climate Experiment (GRACE). Monthly estimates of large-scale variations in the land-water storage are obtained from the satellite data. Evapotranspiration is computed with the water-balance equation using the GRACE land-water solutions, rainfall data from the Global Precipitation Climatology Center and runoff values obtained as 5% of the precipitation. GRACE-derived evapotranspiration values are consistent with the different climatic scenarios observed, and they satisfactorily agree with estimates provided by a global hydrological model. The overall results show that the method used is a valid tool for characterizing the evapotranspiration in the Argentine Pampas and that it can be used to detect and examine changes in the evapotranspiration pattern associated with the occurrence of extreme climatic events. This study illustrates the ability of GRACE to analyze and predict evapotranspiration and other processes on a regional scale in a flatland area.     

长江流域陆地水储量与多源水文数据对比分析

从趋势性、滞后性及相关性三方面,对2002—2013年间GRACE重力卫星反演的长江上游与中游陆地水储量与模型模拟土壤含水量、实测降水和实测径流数据进行了对比分析,并从干旱强度及发展时间两方面评估了标准化陆地水储量指数SWSI、标准化降水指数SPI、标准化径流指数SRI和标准化土壤含水量指数SSMI对区域性干旱的表征能力.结果表明:长江上游地区陆地水储量与降水、径流和土壤水蓄量均无显著变化,而中游地区陆地水储量则与水库蓄量同样具有显著性增加,反映人类活动对中游地区陆地水储量变化有很大影响;各指标指示的各等级干旱月份数量基本相当,但各指标反映的特旱具体月份有较大差别,基于GRACE数据构建的SWSI指标对特大干旱的指示性不好;对比各指标对上游与中游地区干旱事件发展时间,体现出水文干旱、农业干旱对气象干旱存在一定的迟滞关系.     

Global land water storage change from GRACE over 2002–2009; Inference on sea level

Global change in land water storage and its effect on sea level is estimated over a 7-year time span (August 2002 to July 2009) using space gravimetry data from GRACE. The 33 World largest river basins are considered. We focus on the year-to-year variability and construct a total land water storage time series that we further express in equivalent sea level time series. The short-term trend in total water storage adjusted over this 7-year time span is positive and amounts to 80.6 ± 15.7 km³/yr (net water storage excess). Most of the positive contribution arises from the Amazon and Siberian basins (Lena and Yenisei), followed by the Zambezi, Orinoco and Ob basins. The largest negative contributions (water deficit) come from the Mississippi, Ganges, Brahmaputra, Aral, Euphrates, Indus and Parana. Expressed in terms of equivalent sea level, total water volume change over 2002–2009 leads to a small negative contribution to sea level of –0.22 ± 0.05 mm/yr. The time series for each basin clearly show that year-to-year variability dominates so that the value estimated in this study cannot be considered as representative of a long-term trend. We also compare the interannual variability of total land water storage (removing the mean trend over the studied time span) with interannual variability in sea level (corrected for thermal expansion). A correlation of ∼0.6 is found. Phasing, in particular, is correct. Thus, at least part of the interannual variability of the global mean sea level can be attributed to land water storage fluctuations.     

Relation between GRACE-derived surface mass variations and precipitation over Australia

Surface mass changes (SMCs) obtained from time-variable gravity observations of the Gravity Recovery and Climate Experiment (GRACE) satellite mission and precipitation data from the Australian Bureau of Metrology and the Tropical Rainfall Measurement Mission are analysed over the Australian continent to determine whether there is a statistically significant correlation between them. The multiple linear regression analysis and the principal-component analysis techniques are applied in order to reveal the spatial and temporal variability of each data set separately as well as their mutual relationships. The study provides results and their statistical significance for the whole of Australia including the Murray Darling Basin in the southeast. The results suggest a significant decrease in water storage in the southeast of Australia and a dominant annual cycle over the majority of the continent for the four year period considered (January 2003 to December 2006), both in the surface mass and rainfall time series. The study revealed a direct relation between the data sets over most parts of Australia as confirmed by visual comparison and correlation analysis. When compared with precipitation data GRACE-derived SMCs exhibit smoother spatial and temporal variations. The latter is better suited to detect long-term trends in the presence of strong annual signals, which can adversely affect long-term trend estimates. Results regarding the magnitude of the annual signal suggest that only about a fourth of the precipitation's water masses remain sufficiently long in an area to be detected as a gravity change. The respective phases of the annual signals show an average time lag of about 40 days between precipitation and SMCs, suggesting that it takes about one to two months until a temporal gravity observation can detect a precipitation event.     

Monitoring runoff coefficients and groundwater levels using data from GRACE,GLDAS, and hydrometeorological stations: analysis of a Colombian foreland basin

The determination of space–time variation in groundwater accumulation in Colombia’s Eastern Llanos foreland basin from 2003 to 2014 was done using terrestrial water storage (TWS) anomalies identified in two versions of the Gravity Recovery and Climate Experiment (GRACE) data—from the Global Data Center for Space Research (CSR) at the University of Texas at Austin (USA) and from the Institute of Geodesy at the Graz University of Technology (ITSG, Austria)—and also soil moisture storage (SMS) data from the Global Land Data Assimilation System (GLDAS). These data were compared to changes in groundwater storage obtained using the water-budget equation, calculated based on recorded data from hydrometeorological stations. This study confirmed the viability of using satellite information to understand and monitor temporal variation in groundwater recharge in the study area. Temporal variations in TWS, SMS, and groundwater level were shown to correspond to regional rain and drought periods, which are sensitive to climate phenomena such as El Niño and La Niña. Comparing changes in TWS and groundwater level to changes in infiltration and recharge revealed correlation coefficients of 0.56 and 0.98 with CSR data and 0.71 and 0.86 with ITSG data, respectively.     

Mapping groundwater storage variations with GRACE: a case study in Alberta,Canada

The applicability of the Gravity Recovery and Climate Experiment (GRACE) to adequately represent broad-scale patterns of groundwater storage (GWS) variations and observed trends in groundwater-monitoring well levels (GWWL) is examined in the Canadian province of Alberta. GWS variations are derived over Alberta for the period 2002–2014 using the Release 05 (RL05) monthly GRACE gravity models and the Global Land Data Assimilation System (GLDAS) land-surface models. Twelve mean monthly GWS variation maps are generated from the 139 monthly GWS variation grids to characterize the annual GWS variation pattern. These maps show that, overall, GWS increases from February to June, and decreases from July to October, and slightly increases from November to December. For 2002–2014, the GWS showed a positive trend which increases from west to east with a mean value of 12 mm/year over the province. The resulting GWS variations are validated using GWWLs in the province. For the purpose of validation, a GRACE total water storage (TWS)-based correlation criterion is introduced to identify groundwater wells which adequately represent the regional GWS variations. GWWLs at 36 wells were found to correlate with both the GRACE TWS and GWS variations. A factor f is defined to up-scale the GWWL variations at the identified wells to the GRACE-scale GWS variations. It is concluded that the GWS variations can be mapped by GRACE and the GLDAS models in some situations, thus demonstrating the conditions where GWS variations can be detected by GRACE in Alberta.     

Groundwater storage variability and annual recharge using well-hydrograph and GRACE satellite data

Most studies using GRACE (Gravity Recovery and Climate Experiment) data for examining water storage anomalies have rich hydrogeological databases. Here, GRACE data are analyzed for southern Mali, Africa, a region with sparse hydrogeological data. GRACE data (2002?C2008) did not overlap with observed groundwater-level data (1982?C2002). Terrestrial water storage from GRACE was corrected for soil moisture using the Global Land Data Assimilation System (GLDAS) model to obtain monthly groundwater storage anomalies and annual net recharge. Historical storage anomalies and net recharge were determined using the water-table fluctuation method for available observation wells. Average annual net recharge averaged 149.1?mm (or 16.4% of annual rainfall) and 149.7?mm (14.8%) from historical water level and GRACE data, respectively. Monthly storage anomaly lows and peaks were observed in May and September, respectively, but have a shift in peak to November using the corrected GRACE data, suggesting that the GLDAS model may poorly predict the timing of soil-water storage in this region. Notwithstanding problems with the GLDAS model, the soil moisture-corrected GRACE data accurately predict the relative timing and magnitude of groundwater-storage changes, suggesting that GRACE data are valuable for identifying long-term regional changes in groundwater storage in areas with sparse hydrogeological data.     

Hydrological basis of the Devils Lake,North Dakota (USA), terminal lake flood disaster

Devils Lake, a terminal lake in northeast North Dakota (USA), has experienced catastrophic flooding since 1993. From January 31, 1993, to December 31, 2014, lake level rose from 433.62 to 442.44 m, lake area expanded from 179.9 to 653.5 km², and lake volume increased from 0.70 to 3.80 km³. More than $1 billion ($USD) has been spent in government payments to mitigate direct, primary, tangible flood damages. This paper provides a case study of the hydrological basis of the Devils Lake flood disaster. The unique geomorphic setting, paleoclimatic record, and hydroclimatic conditions of the region are summarized, and a wide range of hydroclimatic data is examined to provide a broad understanding of the physical basis of the flood disaster. The primary cause of the disaster was a transition to a sustained wetter climate that resulted in a dramatic response in basin hydrological variables in 1993. The transition from a long-term dry period to a long-term wet period caused the lake water budget to begin to change from an atmosphere-controlled water budget dominated by precipitation input to an amplifier lake water budget dominated by surface runoff input to the lake. Other important hydrological factors include a nonlinear precipitation–runoff relationship following the long-term drought, fill-spill and fill-merge hydrological behavior that is characteristic of wetland complexes, an increase in the lake area-to-basin area ratio, and the critical role of frozen soils in controlling infiltration and runoff production of spring snowmelt. Engineering works to manage lake volume through two outlets have reduced, but not entirely eliminated, future flood risk.

     

前期土壤含水量对水文模拟不确定性影响分析

前期土壤含水量是影响洪水形成的重要流域物理因素,在该次水文模拟中土壤初始含水量采用新安江日模型计算得出.研究中,通过改变日模型模拟的时间长度TP,来研究初始时刻土壤含水量的变化对洪水模拟精度的影响.结果表明:初始土壤含水量对于洪水模拟的精度有显著影响,不同日模型计算时间可以使次洪初始土壤蓄水量W的变化达到42%,而相应的洪峰偏差达到57.7%.土壤和降雨观测数据分析显示,土壤体积含水量与前期累积降雨量有一定地相关关系.为有效解决传统模型与流域真实物理属性数据的融合问题,初步建立了实测土壤体积含水量数据与模型中土壤湿度参数及前期降雨的经验关系.     

Sensitivity of GRACE-derived estimates of groundwater-level changes in southern Ontario,Canada

Amidst changing climates, understanding the world’s water resources is of increasing importance. In Ontario, Canada, low water conditions are currently assessed using only precipitation and watershed-based stream gauges by the Conservation Authorities in Ontario and the Ministry of Natural Resources and Forestry. Regional groundwater-storage changes in Ontario are not currently measured using satellite data by research institutes. In this study, contributions from the Gravity Recovery and Climate Experiment (GRACE) data are compared to a hydrogeological database covering southern Ontario from 2003 to 2013, to determine the suitability of GRACE total water storage estimates for monitoring groundwater storage in this location. Terrestrial water storage data from GRACE were used to determine monthly groundwater storage (GWS) anomaly values. GWS values were also determined by multiplying groundwater-level elevations (from the Provincial Groundwater Monitoring Network wells) by specific yield. Comparisons of GRACE-derived GWS to well-based GWS data determined that GRACE is sufficiently sensitive to obtain a meaningful signal in southern Ontario. Results show that GWS values produced by GRACE are useful for identifying regional changes in groundwater storage in areas with limited available hydrogeological characterization data. Results also indicate that GRACE may have an ability to forecast changes in groundwater storage, which will become useful when monitoring climate shifts in the near future.     

Runoff responses at different watershed scales in semi arid region: exploration of a developed rainfall runoff model (Merguellil and Skhira watershed, Central Tunisia)

Understanding the hydrological response of small and large river basins is crucial for regional climate and hydrology studies. Also, rainfall space–time variability (Known in semi arid climate) has a major influence on hydrological dynamics. As consequent, we developed a software application (with MATLAB) in order to take into account the rainfall space-time variability, and that open a major prospects of studying hydrometeorological effects such scale effect and moving storms. In this context, in order to asses scale and dynamic rainy events effect in hydrologic modelling, this study focuses on instantaneous rainy data in central Tunisia (Merguellil and Skhira watershed): a rainfall runoff modelling was done to investigate basins responses and a developed geomorphology-based transfer function, was applied. A systematic hydro-meteorological analysis have been implemented to understand different types of variability and rainy fields dynamic, the relevance of rainfall network and scale effects. As result, two different behaviours of studied basins are detected. Responses of studied areas are much related to event dynamic (East/West and West/East) and hydrographs change according to event direction.     

青藏高原湖泊变化遥感监测及水量平衡定量估算研究进展

青藏高原湖泊是气候变化的重要指示器,20世纪90年代中期以来,在暖湿化环境下降水增多和冰川冻土加速融化导致的湖泊扩张是青藏高原最为突出的环境变化特征。值得注意的是,湖泊水位变化的空间分布特征和西风带及印度季风带影响区的降水量变化具有高度的空间一致性。严酷的自然环境导致对青藏高原内陆湖泊的实地观测变得难以企及,而遥感技术的发展正好可以克服以上局限,该技术已经成为青藏高原湖泊变化监测的主要研究手段。本文围绕遥感监测技术与方法,综述了青藏高原湖泊面积、水量、冰物候、水体参数以及水量平衡定量估算等方面的研究进展。部分研究以流域为尺度应用多源遥感与水文模型进行水量平衡定量评估,结果表明青藏高原内陆地区的湖泊水量增加的主要贡献因素是降水增多,而冰川融化、冻土消融及其他因素的贡献程度却相对较小。当前,学术界一般认为：大尺度的降水年代际变化是青藏高原湖泊近期变化的主要原因,而冰川冻土加速消融又进一步加速湖泊扩张或抑制了部分湖泊收缩。过去,关于青藏高原湖泊变化的气候响应机制研究大多停留在对降水、蒸发、温度、风速、冰冻圈融化等气候因素的定性描述上;现在,在湖泊水量平衡方面,越来越多的研究开始在定量化方面取得进展;将来,随着更多遥感数据的开放共享,以及更多水文与气象站点的投入使用,将为青藏高原湖泊的水量平衡定量研究提供更好的数据条件。     

Marine records of Holocene climatic variations

Holocene millennial climate variability is smaller than that of the last glaciation, due to the disappearance of large unstable ice sheets. Marine records show that the sea-surface temperature (SST) exhibited small variations, mainly in the high and low latitudes. They may be interpreted as a linear response to the mean annual insolation. Major changes in the hydrological cycle have been evidenced in the Asian and African monsoon area, resulting in enhanced precipitation and large river outflow in the Bay of Bengal and the Gulf of Niger. Enhanced rainfall over the Mediterranean Basin resulted in a weak circulation and sapropel formation below 800-m water depth in the eastern Mediterranean Sea. Finally small changes in the thermohaline circulation and the warm North Atlantic Drift have been detected in the Nordic Seas. The Holocene climatic variability is therefore similar to that of the Quaternary, but with small amplitude, while continents experienced large rainfall variations. To cite this article: J.-C. Duplessy et al., C. R. Geoscience 337 (2005).     

Beach ridges of Dali Lake in Inner Mongolia reveal precipitation variation during the Holocene

Variability in East Asian summer monsoon precipitation during the Holocene remains of debate. In this study, we use a closed lake with well-dated lake beach ridges located on the margin of the East Asian summer monsoon, a region highly sensitive to monsoon precipitation changes, to obtain a temporal sequence of water volume in North China. The elevation of each beach ridge calibrated to the modern lake level was surveyed. Optically stimulated luminescence dating of undisturbed sediments of beach ridges was performed. The lake area and water volume corresponding to each beach ridge were calculated using a digital elevation model. This study reveals relatively reduced monsoon precipitation from ~12 to 7 ka interrupted by strengthening of the monsoon circulation to a maximum from ~7 to ~5 ka and followed by greatly reduced monsoon intensity until the present day. These results demonstrate that changes in the East Asian summer monsoon precipitation may not be directly driven by global temperature or atmospheric CO₂ content. Rather, we suggest that variation in the the monsoon margin precipitation is probably mainly driven by ice volume and subordinately by the summer solar insolation difference between mid-latitude land and low-latitude ocean.     

Research Progress of Groundwater Storage Changes Monitoring in China Based on GRACE Satellite Data

The data acquired by Gravity Recovery and Climate Experiment (GRACE) satellite provides a new way for monitoring groundwater storage changes in China. It is vital to understand its applications in China. This paper systematically reviewed the research progress of groundwater storage monitoring in China based on GRACE data. First, we used the bibliometric analysis and quantitative analysis to clarify trends and characteristics of related studies. Then, we elaborated on the basic principles, methods and uncertainties of groundwater monitoring based on GRACE data. Furthermore, we reviewed the research progress from the aspects of spatial range, accuracies and findings. It was found that the groundwater storage monitoring in China based on GRACE data has gradually received more attention, and the numbers of relevant publications and total citations in both Chinese and English showed an increasing trend. The methods mainly include the principle of water balance and calibration of hydrological models using GRACE satellite data. Most of the relevant studies focused on the North China Plain. The monitoring results are in good agreement with the measured groundwater data, and their correlation coefficients are higher than 0.6. We suggested that the challenges such as low spatial resolution of GRACE data and the uncertainties in monitoring should be considered. In the future, global positioning system, interferometric synthetic aperture radar and groundwater level observation data can be integrated to improve the reliability of groundwater storage monitoring in China.     

Statistical detection and no-detection of rainfall change trends and breaks in semiarid Tunisia—50+ years over the Merguellil agro-hydro-climatic reference basin

Rainfall variability is an important feature of semiarid climates with major effects on hydrology, and beyond on key water-dependent societal aspects. Eventual changes in rainfall variability are a strong driver of change of hydrological processes, resources, and hazards, up to catchment signatures and spatial arrangements. We deal with observed precipitations and subsequent statistical coefficients available from a network of 15 rainfall gauges over and around the Merguellil catchment (1175 km²), with series ranging up to the 1961–2013 period. We look for eventual annual trends and breakpoints with a set of methods: Mann Kendall test, Pettitt test, Hubert segmentation procedure, Buishand U statistic, and Lee Heghinian Bayesian procedure. The results underline oscillation of dry and wet periods; several studied rain gauges (Tella, Oueslatia forêt, Majbar, Kesra forêt, Henchir Bhima, and Haffouz DGRE) denote significant trends in annual precipitation. Some breaks are detected but they are not synchronous. These methods reveal the variability of rainfall regimes in the semiarid region and provide a synoptic view of detection and no-detection of symptoms of change. This work gives opportunities to water stakeholders and climate experts in understanding the relationships between climate variability and water availability.     

Evaluation of the real-time TRMM-based multi-satellite precipitation analysis for an operational flood prediction system in Nzoia Basin,Lake Victoria,Africa

Many researchers seek to take advantage of the recently available and virtually uninterrupted supply of satellite-based rainfall information as an alternative and supplement to the ground-based observations in order to implement a cost-effective flood prediction in many under-gauged regions around the world. Recently, NASA Applied Science Program has partnered with USAID and African-RCMRD to implement an operational water-hazard warning system, SERVIR-Africa. The ultimate goal of the project is to build up disaster management capacity in East Africa by providing local governmental officials and international aid organizations a practical decision-support tool in order to better assess emerging flood impacts and to quantify spatial extent of flood risk, as well as to respond to such flood emergencies more expediently. The objective of this article is to evaluate the applicability of integrating NASA’s standard satellite precipitation product with a flood prediction model for disaster management in Nzoia, sub-basin of Lake Victoria, Africa. This research first evaluated the TMPA real-time rainfall data against gauged rainfall data from the year 2002 through 2006. Then, the gridded Xinanjiang Model was calibrated to Nzoia basin for period of 1985–2006. Benchmark streamflow simulations were produced with the calibrated hydrological model using the rain gauge and observed streamflow data. Afterward, continuous discharge predictions forced by TMPA 3B42RT real-time data from 2002 through 2006 were simulated, and acceptable results were obtained in comparison with the benchmark performance according to the designated statistic indices such as bias ratio (20%) and NSCE (0.67). Moreover, it is identified that the flood prediction results were improved with systematically bias-corrected TMPA rainfall data with less bias (3.6%) and higher NSCE (0.71). Although the results justify to suggest to us that TMPA real-time data can be acceptably used to drive hydrological models for flood prediction purpose in Nzoia basin, continuous progress in space-borne rainfall estimation technology toward higher accuracy and higher spatial resolution is highly appreciated. Finally, it is also highly recommended that to increase flood forecasting lead time, more reliable and more accurate short- or medium-range quantitative precipitation forecasts is a must.