Wet Spells Research Articles

Unraveling the pertinence of drought indices in the changing climate

The increasing divergence/disagreement between the meteorological drought indicators, majorly due to the changing climate conditions, has disputed their pertinency in the monitoring and modeling of drought events. In the present study, we attempted to quantify the divergence between widely used drought indices such as the standardized precipitation index (SPI), standardized precipitation evapotranspiration index (SPEI), and the newly developed standardized net precipitation index (SNEPI) and traced the evolution of this divergence/disagreement. A persistent presence of enhanced dry extremes in the annual divergence of SPEI with SPI and SNEPI was observed, which raises doubts about the utility of traditional drought indices in capturing the changing climatic characteristics. The seasonal dispersion of this annual divergence revealed a strong, spatiotemporally dominant, signal of dryness in the monsoon season by SNEPI, which SPEI failed to unravel. Furthermore, the attribution analysis revealed that the SPI-SPEI disagreements evolved under the influence of the shortwave radiative fluxes. In addition to that, the divergence between SPEI and SNEPI, is driven by the characteristics of wet spells, with the relationship strengthening in the monsoon season and tropical climate zones. All these findings caution us to evaluate the need to incorporate the changing precipitation characteristics before deploying drought indices in operational uses, especially in tropical climate zones.

Relation Between the Madden Julian Oscillation with Wet and Dry Spells During Belg Season Over Ethiopia

The main objective of this study is to explore seasonal impacts of the Madden–Julian oscillation (MJO) on tropospheric circulations affecting Ethiopia during Belg (March–May) rains and associated variability in precipitation. The data used daily rainfall, daily Madden-Julian (MJO) indices, daily Outgoing Longwave Radiation (OLR) and zonal and meridional wind data. The methods used for this study is Correlation and composite analyses are used to establish the association and the relationship between the MJO and rainfall over Ethiopia. A non-significant declining trend in annual rainfall across Ethiopia has been observed over the past three decades trend change per year over by -0.602 mm and P-Value 0.338. The mean length of wet spells 90 days over SNNPR and Southern Oromia Region, and with a least mean length of wet spell is 10 days over Afar, Tigray and western Amhara Region. The results reveals that there is a strong correlation between Ethiopian rainfall and MJO to the west of the region especially around Central and Southeastern parts of the Country. Out of phase (opposite) relationship between the west and the east is also indicating different rain causing mechanisms for the two regions. The rainfall amount also shown to depend on the configuration of the winds at lower and upper levels. Based on composite analysis extreme rainfall events shown to occur during preferential phases of the MJO. Phase 2 coincides with enhanced rainfall, high negative anomaly OLR values as well as westerly and easterly winds configuration at 200hpa and 850hpa while phase 5, 6 and 7 are associated with deficit of rainfall. The inclusion of other modes of variability such as Sea surface Temperatures (SSTs) and the Indian Ocean Dipole (IOD), as predictors recommended in predicting interaseasonal rainfall.

Lagged compound dry and wet spells in Northwest North America under 1.5 °C–4 °C global warming levels

The increasing variability and rapid transitions between hydroclimatic extremes and their compounding economic and environmental effects can cause severe consequences. Understanding the changing characteristics of such transitions, including their spatiotemporal frequency and magnitude is critical to developing effective mitigation and adaptation strategies. In this study, lagged compound dry and wet spells are investigated in Northwest North America (NWNA) based on the Standardised Precipitation Index and Standardised Precipitation Evapotranspiration Index for multiple accumulation periods (1, 3, and 6 months). The indices are estimated based on six downscaled Global Climate Models that participated in the 5th phase of the Coupled Model Intercomparison Project under the Representative Concentration Pathways (RCPs) 4.5 and 8.5, in addition to the Variable Infiltration Capacity hydrologic model simulations. We characterize changing behaviour of the lagged compound dry and wet spells under 1.5 °C–4 °C global warming levels. Projections show overall increases in the frequency of wet and dry swings and decreases in the corresponding transition times in NWNA under climate change. In addition, the magnitude, intensity, and duration of wet and dry components of such lagged compound events are projected to increase. With some differences, both indices identify the entire Columbia and southern Fraser basins as hotspots for frequent compound event occurrences. The study identifies increasing hotspots across the domain affected by abrupt transitions under climate change and asserts the necessity of integrating mitigation measures targeting such lagged compound events into disaster risk reduction strategies.

Impacts of climate extremes on autumn phenology in contrasting temperate and alpine grasslands in China

The frequency and intensity of extreme climate events are expected to increase and have a significant impact on terrestrial ecosystems and the carbon cycle. However, the effects of these events on the end of the growing season (EOS), a crucial phenological phase, are still unclear. Here, we first examined the spatiotemporal patterns of the EOS and extreme climate events in contrasting temperate and alpine grasslands of China during 1982–2015. Then we investigated the effects and mechanisms of the extreme climate factors (i.e., extremely warm, extremely cold, extremely dry, and extremely wet) on EOS based on partial correlation analysis. Our results showed a significant advance trend of EOS in the temperate grasslands (-1.82 days decade-1) while a slightly delaying trend in the alpine grasslands (0.27 days per decade). For both grasslands, we found increased extremely warm climate as represented by the Warm spell duration indicator (WSDI) and decreased trends in extremely cold (Cold spell duration indicator, CSDI), extremely dry (Dry spell duration indicator, CDD), and extremely wet (Wet spell duration indicator, CWD). We found a significant negative correlation between WSDI and EOS in the alpine grassland, while this relationship in temperate grasslands was more complex. Multiple factors such as the vapor pressure deficit (VPD), soil moisture, and solar radiation, might be responsible for these patterns. Besides, EOS exhibited neither dominant-negative nor dominant-positive responses to CSDI (extreme cold), CDD (extremely dry), and CWD (extremely wet), with varying responses among biomes and for soil moisture levels. Our findings demonstrate that various extreme climate factors need to be considered to improve autumn phenology predictions and our understanding of the impact on the carbon balance in a changing climate.

Observed Changes in Rainfall and Characteristics of Extreme Events in Côte d’Ivoire (West Africa)

This study evaluates how the characteristics of daily rainfall and extreme events in Côte d’Ivoire changed during 1961–2015 using the rain gauge observation network of the National Meteorological Service (SODEXAM). The results indicate that the northern and southern parts of Cote d’Ivoire experienced a change from a wet to a dry period, with cut-offs in 1982 and 1983, respectively. In the northern part, this dry period was marked by a decrease in rainfall intensity, the length of wet spells, and the contribution of heavy and extreme rainfall, as well as an increase in the number of rainy days and a decrease in the length of dry spells. Over the southern part, this dry period was marked by an increase in the maximum length of dry spells associated with an increase in the maximum 1-day and 5-day precipitation events. The western part of Côte d’Ivoire experienced a late cut-off from the wet to dry period in 2000; the dry period was associated with a decrease in the number of rainy days, rainfall intensities, and maximum length of wet spells. Changes in the central part of Cote d’Ivoire presented high variability, and trends were less marked, even though a cut-off from a wet to dry period was detected in 1991. This study shows that Côte d’Ivoire, which is located in a subhumid and humid region and has an economy dependent on agriculture (especially cash crops, which comprise 60% of the GDP), is experiencing dry spells that are increasing in frequency and length. Combined with deforestation to increase production, this situation could lead to desertification and compromise the sustainable development goals of the country. The contribution of heavy rainfall was found to increase during the last 15 years, increasing the overall risk of floods, especially in urban areas where city authorities and populations are not prepared, thereby threatening infrastructure and human security.

Precipitation Bias Correction: A Novel Semi‐parametric Quantile Mapping Method

AbstractBias correction methods are used to adjust simulations from global and regional climate models to use them in informed decision‐making. Here we introduce a semi‐parametric quantile mapping (SPQM) method to bias‐correct daily precipitation. This method uses a parametric probability distribution to describe observations and an empirical distribution for simulations. Bias‐correction techniques typically adjust the bias between observation and historical simulations to correct projections. The SPQM however corrects simulations based only on observations assuming the detrended simulations have the same distribution as the observations. Thus, the bias‐corrected simulations preserve the climate change signal, including changes in the magnitude and probability dry, and guarantee a smooth transition from observations to future simulations. The results are compared with popular quantile mapping techniques, that is, the quantile delta mapping (QDM) and the statistical transformation of the CDF using splines (SSPLINE). The SPQM performed well in reproducing the observed statistics, marginal distribution, and wet and dry spells. Comparatively, it performed at least equally well as the QDM and SSPLINE, specifically in reproducing observed wet spells and extreme quantiles. The method is further tested in a basin‐scale region. The spatial variability and statistics of the observed precipitation are reproduced well in the bias‐corrected simulations. Overall, the SPQM is easy to apply, yet robust in bias‐correcting daily precipitation simulations.

Turkana Low-Level Jet Influence on Southwest Ethiopia Climate

Abstract The Turkana Jet in northern Kenya is shown to modulate the climate of southwest Ethiopia’s Omo River Valley using in situ hydrometeorological data, satellite measurements, and atmospheric reanalyses from decadal to diurnal time scales. Temporal statistics from lowland (2.5°–5°N, 35°–38°E) and highland (6°–9°N, 35°–38°E) areas show that 850-hPa westward airflow over Lake Turkana is stronger in March and October but is weakened when western Indian Ocean sea temperatures become warmer than usual at intervals of 2–7 years. A case study on 24 March 2019 reveals how a stronger Turkana Jet induces warming and drying of the Omo Valley. A second case study on 27 September 2018 reveals Hadley cell subsidence over the southern flank of the Turkana Jet. We demonstrate how nocturnal airflow draining off the mountains joins the channelized jet. Satellite and atmospheric reanalyses exhibit realistic diurnal cycles in the east Omo mountains, but some products have incorrect phase and warm bias. Omo Valley soil moisture and runoff exhibit little trend in historical records and model projections; however, unpredictable multiyear wet and dry spells and a growing demand for water are ongoing concerns.

Understanding the Association between Cattle Tick-borne Diseases and Climate variability in Mbarara District, Western Uganda

A study to examine the association between tick-borne diseases and climate variability in cattle keeping communities in Mbarara district in South in Western Uganda was undertaken aiming at inputting into the tactical and strategic control of the diseases in the largely livestock dependant region in the country. In a multi-sectoral priority setting exercise, tick borne diseases was top on the list of constraints responsible for cattle mortality and reduced productivity. A clinical tick- borne disease data analyzed basing on standard microscopic procedures, including capillary agglutination test and giemsa stain, was obtained from Mbarara veterinary clinic. 
 The disease data was matched with rainfall data from 27 rain gauge stations obtained from National meteorological stations and recording centers scattered within the district covering a period of 56 years since 1950. The number of wet spells and disease cases showed that disease cases were positively correlated with rainfall at a 95% confidence level (R2= 0.56). Disease cases exhibited peak cyclical patterns related to rainfall during the transmission season during October, November and December with extreme peaks occurring every other year while Significant (r2=0.536) variability was observed for the positive trend in March - April -May seasonal rainfall for one of the three zones. Additionally, the results in this study indicate that rainfall is a substantial determinant of seasonal activity of the transmitting vectors from season to season and from year to year.

Wet and Dry Spell Analysis for Crop Planning in Central Plain Zone of Punjab Using Markov Chain Method

A study was conducted during 2017–2018 at department of climate change and agricultural meteorology, PAU, Ludhiana to find out the initial and conditional probability of occurrence of wet and dry spell of rainfall at different locations of Punjab, the analysis was carried out using Markov Chain Method (MCM). The historical data of rainfall for three locations of Punjab viz. Amritsar (1971–2017), Ludhiana (1971–2018) and Patiala (1971–2018) were collected from the Department of Climate Change and Agricultural Meteorology, PAU, Ludhiana and Met Centre, India Meteorological Department, Chandigarh. At Amritsar the chances of occurrence of wet spell were highest during 28th SMW i.e., 72% followed by 68% during 30th and 31st SMW respectively. The conditional probability calculated at Ludhiana showed that the probability of wet spell followed by wet spell was highest (71%) during 28th SMW followed by 66 per cent during 30th and 32nd SMW. At Patiala the probability of wet spell was highest (69%) during 33rd week followed by 63% during 29th SMW. The conditional probability also showed that dry spell followed by dry spell occurred more frequently than wet spell followed by wet spell.

Evaluation and future projection of the extreme precipitation over India and its homogeneous regions: A regional earth system model perspective

AbstractA regional earth system model (ROM) was used to examine the projected change in the precipitation extremes (PEs) and associated dynamical and thermodynamical processes over India during the Indian summer monsoon (ISM). In this regard, PEs are computed for India, its six homogeneous regions and subregions the Western Ghats (WG) and central India (CI). The changes are computed for mid‐future (2040–2069: MDF) and far‐future (2070–2099: FRF) with respect to the historical period (1969–2000). ROM showed better resemblance with observation in simulating PEs over other regional climate models (RCMs) that participated in the CORDEX‐CORE simulation. The intense rainfall (95th percentile: R95) is expected to be enhanced over most of the region during MDF that further intensifies in FRF except CNE (central northeast) and NEI (northeast India), where the increase in R95 was restricted only up to MDF. Interestingly, very intense rainfall (99.9th percentile: R99) showed robust increases in both MDF and FRF for all regions. Additionally, long wet (dry) events were shortened (lengthen). Moreover, the short wet and dry spell frequency has increased, while the duration of the wet (dry) spell has decreased (increased) in both time slices over India with noticeable regional variation. This is attributed to the strong cyclonic circulation, reduced vertical wind shear and enhanced moisture transport during the ISM in both time slices. It is very important to highlight the substantial changes in the precipitation extremes to have better planning and strategies that will be helpful to minimize the incurred losses.

Variations in Droughts and Wet Spells and Their Influence in the Beijing–Tianjin–Hebei Region

Variations in Droughts and Wet Spells and Their Influence in the Beijing–Tianjin–Hebei Region

Bivariate Hazard Assessment of Combinations of Dry and Wet Conditions between Adjacent Seasons in a Climatic Transition Zone

Accumulated evidence reminds one that abrupt transitions between dry and wet spells, though attracting less attention, have harmful influences upon global continents as extensively investigated droughts and floods. This study attempts to incorporate dryness–wetness transitions into the current hazard assessment framework through bivariate frequency analysis and causal attribution from a teleconnection perspective. In the study, regional dry and wet conditions are monitored using the multivariate standardized drought index (MSDI) which facilitates the integrated evaluation of water deficits/surplus from a combined viewpoint of precipitation (largely denoting the received atmospheric water) and runoff (representing an important source of surface water). On such a basis, a copula-based method is subsequently utilized to calculate joint return periods of dryness–wetness combinations in three (i.e., moderate, severe and extreme) severity scenarios. The changing frequency of diverse dryness–wetness combinations is also estimated under a changing climate using a 25-year time window. Furthermore, the cross-wavelet transform is applied to attribute variations in dry and wet conditions to large-scale climate indices, which benefits the early warning of dryness–wetness combinations by providing predictive information. A case study conducted during 1952–2010 in the Huai River basin (HRB)—a typical climatic transition zone in China—shows that the HRB is subject to prolonged dryness with the highest frequency, followed by the abrupt transition from dryness to wetness. Spatially, abrupt dryness–wetness transitions are more likely to occur in the southern and central parts of the HRB than in the rest of the proportion. The past half-century has witnessed the dominantly higher frequency of occurrence of dryness–wetness combinations under three severity scenarios. In particular, the occurrence of the continued dry/wetness escalates more rapidly than transition events under climate change. Moreover, a preliminary attribution analysis discloses the link of the dry and wet conditions in the HRB with climate indices, such as the El Niño southern oscillation, the Pacific decadal oscillation and the Arctic oscillation, as well as sunspot activities. The results of the study enrich the current atlas of water-related hazards, which may benefit more effective hazard mitigation and adaptation.

Three-decade assessment of dry and wet spells change across Iran, a fingerprint of climate change

Extended periods of hydro-climate extremes with excessive or scarce rainfall associated with high or low temperatures have resulted in an imbalanced water cycle and inefficient socio-economic systems in several regions of Iran. However, there is a lack of comprehensive investigations on short-term to long-term variations in timing, duration, and temperature of wet/dry spells. This study bridges the current gap through a comprehensive statistical analysis of historical climatic data (1959–2018). Results indicated that the negative tendency of the accumulated rainfall (− 0.16/ − 0.35 mm/year during the past 60/30 years) in 2- to 6-day wet spells had made significant contributions to the ongoing downward trend in annual rainfall (− 0.5/ − 1.5 mm/year during the past 60/30 years) owing to a warmer climate condition. Warmer wet spells are likely responsible for precipitation patterns changes in snow-dominated stations since their wet spells temperature has more than threefold growth with increasing distance to coasts. The most detected trends in climatic patterns have started in the last two decades and become more severe from 2009 to 2018. Our results confirm the alteration of precipitation features across Iran due to anthropogenic climatic change, and suggest expected increase in air temperature would likely result in further dry and warm conditions over the coming decades.

Long-term spatio-temporal variability and change in rainfall over Ghana (1960–2015)

Assessment of the change in the characteristics of precipitation for more than half a century (1960–2015) is important for determining the extent of climate change on the country Ghana, and more specifically, the Northern Savannah Agro-ecological Zone (NSAZ). This is because the change in the attributes of rainfall has a direct impact on the quality of livelihood and is crucial not only for the sustenance of natural systems but also for agriculture productivity and the supply of food. The analysis involved the determination of the Daily Precipitation Analysis (Annual Total precipitation, Number of wet days, Number of dry days, Number of wet spells, and Number of dry spells) for the period and trend analysis using Mann-Kendall test and Sen's slope estimation. The following climate extreme indices; R10mm, R20mm, R25mm, CDD, CWD, PRCPTOT, SDII were also computed to assess the level of change in rainfall characteristics for the country. It is observed that Inter-annual, decadal changes and the general trend in Total precipitation (PRCPTOT) show a decline which is higher for the country than for the NSAZ. On the other hand, NSAZ has a higher variability observed in terms of the standard deviation and the coefficient of Variation (CoefVar). There is a general drying up of the climate evident in the decline in rainfall amount (PRCPTOT) and intensity (SDII), and this pattern exhibits a latitudinal decrease from the south (5°N) to the north (11°N). We observe the decrease in PRCPT from latitude 4°N up to latitude 10°N with some exceptional years of increases, however, from latitude 10.3°N up to 11°N, there is a steep increase in the driest part of the country especially to the north east. SDII is the only precipitation indices which have a positive and significant relationship with the AMO for both national and Zone. All other indices have Negative and insignificant values of the relationship AMO. NAO has a negative correlation with all the Precipitation indices except CDD and Dry days. This indicates that as NAO increases, PRCPTOT, Wet days, CWD, R10mm, R20mm, R25mm, and SDII decreases, or vice versa.

Untangling the importance of dynamic and thermodynamic drivers for wet and dry spells across the Tropical Andes

Andean vegetation and agriculture depend on the patterns of rainfall during the South American monsoon. However, our understanding on the importance of dynamic (upper-level wind circulation) as compared to thermodynamic (Amazon basin moisture) drivers for Andes rainfall remains limited. This study examines the effect of these drivers on 3–7 day wet and dry spells across the Tropical Andes and assesses resulting impacts on vegetation. Using reanalysis and remote sensing data from 1985–2018, we find that both dynamic and thermodynamic drivers play a role in determining the rainfall patterns. Notably, we show that the upper-level wind is an important driver of rainfall across the entire Tropical Andes mountain range, but not in the Amazon lowlands, suggesting a crucial role of topography in this relationship. From thermodynamic perspective, we find wet spell conditions to be associated with increased moisture along the Andes’ eastern foothills accompanied by a strengthened South American low-level jet, with moisture lifted into the Andes via topography and convection for all considered regions. Our results suggest that while changes in Amazon basin moisture dominate rainfall changes on daily time scales associated with three day spells, upper-level dynamics play a more important role on the synoptic time scale of 5–7 day spells. Considering impacts on the ground, we find that only 5–7 day spells in the semi-arid Andes have a prolonged effect on vegetation. Our study emphasizes the need to consider both dynamic and thermodynamic drivers when estimating rainfall changes in the Tropical Andes, including in the context of future climate projections.

Occurrence of wet and dry spells of rainfall in Bagan, Myanmar

Occurrence of wet and dry spells of rainfall in Bagan, Myanmar

Springtime Southwest Cloud Bands in the Central Caribbean

Abstract Southwest cloud bands during spring (April and May) bring rains to central Caribbean islands at the end of the dry season. A cluster analysis of daily 500-hPa geopotential height fields for 1980–2021 identifies a low-west–high-east dipole pattern related to Pacific–North America response to El Niño–Southern Oscillation (ENSO) and springtime wet spells over the Dominican Republic and Puerto Rico. The regional dipole and local rain time series are ranked to identify the top 10 cases for analysis of meteorological conditions. Hovmöller plots of midlevel meridional wind and specific humidity during April 1983 and May 1986 wet spells reveal a standing Rossby wave train pattern that converges moisture onto the leading edge of a subtropical trough. Composite vertical sections during Caribbean Sea wet spells reveal lower easterly–upper westerly wind anomalies over South America associated with the equatorial Madden–Julian oscillation. Thunderstorm clusters within the southwesterly airflow induce multiday wet spells and flash floods. A second statistical method demonstrated how ENSO underpins Caribbean spring climate anomalies via tropical ocean–atmosphere Rossby wave coupling. Historical trends and long-range projections indicate that springtime tropical–midlatitude interactions may diminish due to an accelerating Hadley cell and retreating jet stream, leading to a delayed onset of the wet season across the Antilles Islands.

On the Structure of the Intermittency of Rainfall

Quantification of rainfall intermittency via. interevent time distribution, series of continuous wet spells (burst size) and variability in interevent times between rainfall events is essential for planning and management of water resources and hydrologic extremes. However, their structure, quantification and association with long-term climatology are less explored. In this paper, a complex system-based measure – burstiness – is used to quantify the variability of interevent times across six meteorologically homogenous zones of India. It is observed that burstiness is related to the burst size as well as long-term rainfall climatology. The existence of unimodal and bimodal structure in burstiness distribution reveals the uniqueness and differences in the rainfall patterns. The differences in sensitivity of rainfall to burstiness highlight the role of interplay between climate-landscape and reveals the importance of the intermittent structure of rainfall. The study provides an approach to model intermittency by preserving the temporal structure of the interevent time distribution.

Longer dry and wet spells alter the stochasticity of microbial community assembly in grassland soils

Climate change is increasing the duration of alternating wet and dry spells. These fluctuations affect soil water availability and other soil properties which are crucial drivers of soil microbial communities. While soil microbial communities have a moderate capacity to recover once a drought ceases, the expected alternation of strongly opposing regimes can challenge their capacity to adapt. Here, we set up experimental grassland mesocosms where precipitation frequency was adjusted along a gradient while holding total precipitation constant. The gradient varied the duration of wet and dry spells from 1 to 60 days during a total of 120 days, where we hypothesized that especially intermediate durations would increase the importance of stochastic community assembly due to frequent alternation of opposing environmental regimes. We examined bacterial and fungal community composition, diversity, co-occurrence patterns and assembly mechanisms across these different precipitation treatments. Our results show that 1) intermediate regimes of wet and dry spells increased the stochasticity of microbial community assembly whereas microbial communities at low and high regimes were subjected to more deterministic assembly, and 2) more persistent precipitation regimes (>6 days duration) reduced the fungal diversity and network connectivity but had little effect on bacterial communities. Collectively, these findings indicate that longer alternating wet and dry events lead to a less predictable and connected soil microbial community. This study provides new insight into the likely mechanisms through which precipitation persistence alters soil microbial communities and their predictability.

Rainfall Wet Spells Variability Across Temperature Mean‐Change Years in the Northwestern Himalayan Region

AbstractTemperatures have risen at a faster rate across various mountainous regions around the world. A study of the changing rainfall patterns and their spatiotemporal variability is critical for agricultural, water resource, and hydrological planning and management. The goal of this research is twofold: first, using functional data analysis climate change hotspots are determined, which in turn identified most temperature increases in high elevations. Second, these hotspots are utilized to investigate the impact of temperature changes on the frequency of extreme rainfall events in this Northwestern Himalaya region. Our study observed that the frequency of rainfall extremes, such as, at the 90th, 95th, and 99.99th percentile values, is found to be increasing mostly in lower Himalayan regions. A warmer atmosphere leads to heavy precipitation events as the capacity of air to hold moisture increases with the increase in temperature. The continuous temperature rise possibly indicates an increase in extreme rainfall events in the region. Further, this study reports an interesting finding that can help us better understand the impact of climate change in the region: the frequency of shorter wet spells has increased around the recent mean‐change year, whereas the frequency of long spells has reduced. The frequency of longest wet spells shows a decrease across all seasons, leading to drought in the higher altitude region, whereas the short‐wet spell frequency has increased in the lower altitude regions. Insight into the changing patterns of rainfall is crucial for hydrological and agricultural management.