Conceptual Water Balance Model Research Articles

Statistical blending of global-gridded climatological products: an approach to inverse hydrological model

Abstract The growing use of global-scale environmental products in hydro-climatic modeling has increased the variety of their applications and the complications of their uncertainties and evaluations. Researchers have recently turned to statistical blending of these products to achieve optimal modeling. The proposed statistical blending in this study includes five large-scale and satellite precipitation (CHIRPS, ERA5-Land of ECMWF, GPM (IMERG), TRMM, and Terra) and evapotranspiration (GLEAM, SSEBop, MODIS, Terra, and ERA) products committed in three modeling scenarios. The blending procedures are organized using a conceptual water balance model to achieve the best precipitation and evapotranspiration results for the conceptual production of streamflow using hydrological inverse modeling. Based on the results, the proposed blending procedures of precipitation and evapotranspiration improved the performance of the model using different statistical metrics. In addition, the results show the conformity of the pattern and behavior of the blended precipitation calculated using the moving least square method in the study area. This happened by changing the estimation based on in situ values, particularly in cold months considering the orographic/snow effects. The combining method provides a good fusion procedure to improve the realistic estimation of precipitation and evapotranspiration in ungagged watersheds as well.

Constraints on the Ratio between Tropical Land and Ocean Precipitation Derived from a Conceptual Water Balance Model

Abstract Which processes control the mean amounts of precipitation received by tropical land and ocean? Do large-scale constraints exist on the ratio between the two? We address these questions using a conceptual box model based on water balance equations. With empirical but physically motivated parameterizations of the water balance components, we construct a set of coupled differential equations that describe the dynamical behavior of the water vapor content over land and ocean as well as the land’s soil moisture content. For a closed model configuration with one ocean and one land box, we compute equilibrium solutions across the parameter space and analyze their sensitivity to parameter choices. The precipitation ratio χ, defined as the ratio between mean land and ocean precipitation rates, quantifies the land–sea precipitation contrast. We find that χ is bounded between zero and one as long as the presence of land does not affect the relationship between water vapor path and precipitation. However, for the tested parameter values, 95% of the obtained χ values are even larger than 0.75. The sensitivity analysis reveals that χ is primarily controlled by the efficiency of atmospheric moisture transport rather than by land surface parameters. We further investigate under which conditions precipitation enhancement over land (χ > 1) would be possible. An open model configuration with an island between two ocean boxes and nonzero external advection into the domain can yield χ values larger than one, but only for a small subset of parameter choices, characterized by small land fractions and a sufficiently large moisture influx through the windward boundary.

The use of the pilot points method on groundwater modelling for a degraded aquifer with limited field data: the case of Lake Karla aquifer

Abstract Groundwater depletion poses a major threat to global groundwater resources with increasing trends due to natural and anthropogenic activities. This study presents a surface-groundwater framework for water resources modelling of ill-posed problems in hydrogeologically data-scarce areas. The proposed framework is based on the application of a conceptual water balance model and composed of surface hydrological (UTHBAL) and groundwater flow simulation with the integration of a Newton formulation of the MODFLOW-2005 code (MODFLOW-NWT) and PEST suite modules. The groundwater simulation includes a preprocessor tool for automated calibration and a post-processor tool for automated validation. The methodology was applied to a rural region of Central Greece, Lake Karla Basin, which is degraded due to groundwater resources overexploitation to cover irrigation water demands. The aquifer is modelled focusing on a precise simulation–validation procedure of the conceptual model. The groundwater model was calibrated with the calibration preprocessor tool for spatially distributed hydraulic conductivity with the pilot points method. The calibration process achieved satisfactory results as validated by the post-process analysis of observed and simulated water levels. The findings for the groundwater budget indicate that the groundwater system is still under intense pressure even though farming activity in recent years has turned to less water-intensive crops. HIGHLIGHT My research deals with the pilot points method on groundwater modelling in an area with scarce hydrogeologic data.

Quantifying groundwater sensitivity and resilience over peninsular India

AbstractGroundwater in India plays an important role to support livelihoods and maintain ecosystems and the present rate of depletion of groundwater resources poses a serious threat to water security. Yet, the sensitivity of the hydrological processes governing groundwater recharge to climate variability remains unclear in the region. Here we assess the groundwater sensitivity (precipitation–recharge relationship) and its potential resilience towards climatic variability over peninsular India using a conceptual water balance model and a convex model, respectively in 54 catchments over peninsular India. Based on the model performance using a comprehensive approach (Nash Sutcliffe Efficiency [NSE], bias and variability), 24 out of 54 catchments are selected for assessment of groundwater sensitivity and its resilience. Further, a systematic approach is used to understand the changes in resilience on a temporal scale based upon the convex model and principle of critical slowing down theory. The results of the study indicate that the catchments with higher mean groundwater sensitivity (GWS) encompass high variability in GWS over the period (1988–2011), thus indicating the associated vulnerability towards hydroclimatic disturbances. Moreover, it was found that the catchments pertaining to a lower magnitude of mean resilience index incorporates a high variability in resilience index over the period (1993–2007), clearly illustrating the inherent vulnerability of these catchments. The resilience of groundwater towards climatic variability and hydroclimatic disturbances that is revealed by groundwater sensitivity is essential to understand the future impacts of changing climate on groundwater and can further facilitate effective adaptation strategies.

Modeling Catchment-Scale Nitrogen Losses Across a Land-Use Gradient in the Subtropics

Changing land use in subtropical and tropical catchments to farmland can result in higher nitrogen (N) loss to aquatic ecosystems. Here, we developed a lumped water and N balance model to estimate regional N losses to creeks at catchment scale within understudied subtropical catchments in Australia. The conceptual water balance model CoCa-RFSGD was extended by the nitrogen mass balance in top and sub soil by adding nitrogen cycle transformation estimates depending on meteorological, soil and land use properties. The model estimates the impact of pristine and agricultural land use on catchment-wide water quality using only loworder creek samples as water quality measurements of nitrate and nitrite (NOx), with increased model performance with increased agricultural coverage. The model revealed that an agricultural proportion of 3% in the study site drove a 3.5-fold increase of N losses to creeks and a 6.7-fold increase of N losses to the atmosphere compared to catchments without agriculture. Agricultural land use lost 92 kg-N ha−1, of which 85% evaded to the atmosphere and 15% discharged via surface waters. A change from forest to cleared land may increase the total denitrification potential of a catchment. Overall, our lumped model provides a simple but effective tool to upscale local aquatic water quality measurements to the catchment scale, allowing assessment of changing land use on aquatic N loads in areas with limited data availability.

HYBRID MODELING: FUSION OF A DEEP LEARNING APPROACH AND A PHYSICS-BASED MODEL FOR GLOBAL HYDROLOGICAL MODELING

Abstract. Process-based models of complex environmental systems incorporate expert knowledge which is often incomplete and uncertain. With the growing amount of Earth observation data and advances in machine learning, a new paradigm is promising to synergize the advantages of deep learning in terms of data adaptiveness and performance for poorly understood processes with the advantages of process-based modeling in terms of interpretability and theoretical foundations: hybrid modeling. Here, we present such an end-to-end hybrid modeling approach that learns and predicts spatial-temporal variations of observed and unobserved (latent) hydrological variables globally. The model combines a dynamic neural network and a conceptual water balance model, constrained by the water cycle observational products of evapotranspiration, runoff, snow-water equivalent, and terrestrial water storage variations. We show that the model reproduces observed water cycle variations very well and that the emergent relations of runoff-generating processes are qualitatively consistent with our understanding. The presented model is – to our knowledge – the first of its kind and may contribute new insights about the dynamics of the global hydrological system.

A unified framework of water balance models for monthly, annual, and mean annual timescales

At present, many conceptual water balance models have been proposed on monthly, annual, and mean annual timescales. With the increasing applications of these models, an emerging question is whether the water balance models on different timescales have some commonalities and can be integrated. To this end, this study established and applied a practical unified framework of water balance models that can be applied to different timescales. The framework was first developed on monthly timescale, where the water balance was captured by combining the “abcd” model and Budyko hypothesis with four parameters. Then, this framework was extended to annual and mean annual timescales under which certain parameters can be eliminated or assumed to be certain values. To be specific, on the annual timescale, the water balance was simulated by a Budyko-type model incorporating the water storage change; on the mean annual timescale the water balance was further simplified into a Budyko-type model which neglects the water storage change. Thus, all of the three typical water balance models on different timescales were unified to a general framework. The models were applied to 437 catchments in the contiguous United States with satisfying results achieved. Considering the water storage changes can improve the performance of annual water balance models in regions with clear interannual carrying water storage. Furthermore, the water balance models on different timescales share common supply and demand limits which is similar to Budyko hypothesis.

A proportionality-based multi-scale catchment water balance model and its global verification

Unifying the description of catchment hydrological partitioning across spatial and temporal scales has long been an important research topic within the hydrological community. As an effort to that, here we develop a conceptual water balance model based on the proportionality hypothesis (denoted PWBM) and for the first time, test the proportionality hypothesis using hydrologic observations across global catchments at varying time scales. The PWBM has a transparent and parsimonious model structure with only two model parameters, and requires precipitation, potential evapotranspiration and leaf area index as model inputs. To test PWBM, we apply the model to simulate streamflow (Q), evapotranspiration (E) and storage change (ΔS) in 22 large basins and 255 small basins globally and find an overall good model performance in reproducing all three water balance components at the daily (only in small basins), monthly, seasonal, annual and mean-annual time scales. Compared with three other conceptual hydrological models developed for specific time scales, the PWBM substantially outperforms the SCS model at the daily scale and the ABCD model at the monthly scale and performs similarly as the long-standing Budyko model at the mean-annual scale. In summary, our study verifies the robustness of PWBM and offers convincing evidence regarding the applicability of the proportionality hypothesis for enhanced hydrological system understanding at multiple spatial and temporal scales.

Improving monthly streamflow forecasts through assimilation of observed streamflow for rainfall-dominated basins across the CONUS

Among different sources of uncertainty in hydrologic modeling (i.e., model structure, parameter estimation, input data, etc.), consecutive error reduction of model initial conditions can prevent a model from drifting away from reality and consequently improving model estimates. Most approaches that evaluated the correction of initial conditions through data assimilation (DA) have focused on improving hydrologic model simulations (i.e., under observed forcings) rather than evaluating the model performance in a forecasting context. This paper investigates the utility of Ensemble Kalman Filter (EnKF) data assimilation in which available observed streamflow is exploited to update state variables of a conceptual water balance model for forecasting monthly streamflow over 340 rainfall-dominated river basins across the contiguous United States (CONUS). Our results demonstrate that after EnKF application, streamflow simulation skill improves in terms of both Relative Root Mean Square Error (R-RMSE) and correlation coefficient (CC) for almost 90% of the selected river basins. Evaluating the model performance under different flow conditions shows that EnKF has stronger positive effect on monthly low flow predictions comparing to monthly high flows particularly during the summer season. The utility of EnKF is also assessed in the context of 1-month ahead streamflow forecasting. Due to the updated model initial conditions, streamflow forecasts are improved throughout the year even though the skill in hydrologic forecasts is predominantly dependent on the accuracy of precipitation forecasts.

Expanding Rubber Plantations in Southern China: Evidence for Hydrological Impacts

While there is increasing evidence concerning the detrimental effects of expanding rubber plantations on biodiversity and local water balances, their implications on regional hydrology remain uncertain. We studied a mesoscale watershed (100 km2) in the Xishuangbanna prefecture, Yunnan Province, China. The influence of land-cover change on streamflow recorded since 1992 was isolated from that of rainfall variability using cross-simulation matrices produced with the monthly lumped conceptual water balance model GR2M. Our results indicate a statistically significant reduction in wet and dry season streamflow from 1992 to 2002, followed by an insignificant increase until 2006. Analysis of satellite images from 1992, 2002, 2007, and 2010 shows a gradual increase in the areal percentage of rubber tree plantations at the watershed scale. However, there were marked heterogeneities in land conversions (between forest, farmland, grassland, and rubber tree plantations), and in their distribution across elevations and slopes, among the studied periods. Possible effects of this heterogeneity on hydrological processes, controlled mainly by infiltration and evapotranspiration, are discussed in light of the hydrological changes observed over the study period. We suggest pathways to improve the eco-hydrological functionalities of rubber tree plantations, particularly those enhancing dry-season base flow, and recommend how to monitor them.

Assessing the Hydrological Effect of Climate Change on Water Balance of a River Basin in Northern Greece

In this work, the impacts of climate change on the water resources of the Olynthios River Basin in Northern Greece, were assessed. For this purpose, the climate change scenarios SRES and RCPs were used (SRES A1B, Α2 and RCP4.5, 8.5) - which were taken from two climate models, CGCM3.1/T63 and CanESM2, respectively - for two time periods (2031-2050 and 2081-2100) and for the baseline period (1981-2000). The downscaling was performed using the weather generator ClimGen. The monthly water balance of the Olynthios River Basin was estimated with the use of a conceptual water balance model. Results showed that the annual runoff of the river basin of Olynthios will decrease in response to climate change under all scenarios for both time periods. The results highlight the necessity for adequate adaptation strategies which could improve agricultural water management and reduce the impacts of climate change on agriculture.

Hydrological Process Simulation of Inland River Watershed: A Case Study of the Heihe River Basin with Multiple Hydrological Models

Simulating the hydrological processes of an inland river basin can help provide the scientific guidance to the policies of water allocation among different subbasins and water resource management groups within the subbasins. However, it is difficult to simulate the hydrological processes of an inland river basin with hydrological models due to the non-consistent hydrological characteristics of the entire basin. This study presents a solution to this problem with a case study about the hydrological process simulation in an inland river basin in China, Heihe River basin. It is divided into the upper, middle, and lower reaches based on the distinctive hydrological characteristics in the Heihe River basin, and three hydrological models are selected, applied, and tested to simulate the hydrological cycling processes for each reach. The upper reach is the contributing area with the complex runoff generation processes, therefore, the hydrological informatic modeling system (HIMS) is utilized due to its combined runoff generation mechanisms. The middle reach has strong impacts of intensive human activities on the interactions of surface and subsurface flows, so a conceptual water balance model is applied to simulate the water balance process. For the lower reach, as the dissipative area with groundwater dominating the hydrological process, a groundwater modeling system with the embedment of MODFLOW model is applied to simulate the groundwater dynamics. Statistical parameters and water balance analysis prove that the three models have excellent performances in simulating the hydrological process of the three reaches. Therefore, it is an effective way to simulate the hydrological process of inland river basin with multiple hydrological models according to the characteristics of each subbasin.

APPLICATION OF A CONCEPTUAL WATER BUDGET MODEL FOR SALDA LAKE, (BURDUR/ TURKEY)

Sustainable water resources management is a priority issue today. One of the major problems in the sustainable usage of lakes is the estimation of water budget components. The determination of the water budget of lakes is fundamental to an understanding of their hydrological characteristics. The Salda Lake is an inland closed basin and located within the Lake District of Turkey. In addition, the Salda Lake is one of the important wetlands of Turkey and is in the status of protected areas. Therefore, the Salda Lake is indispensable water source for region. The Salda Lake area is 44.7 km2 and lake level is 1136.5 m. In this study, conceptual water balance model of the Salda Lake was developed. Recharge of the Salda Lake is supplied from especially precipitation, surface and groundwater inflow. The directly recharge from the precipitation was calculated as 22.04 (x106) m3/year. The discharge components of the lake are evaporation. The evaporation amount from the lake was determined as 53.98 (x106) m3/year. The unmeasured recharge from groundwater was calculated as 26.33 (x106) m3/year. According to rainfall, evaporation and the lake water level relations, rainfall is dominantly effective on the lake water level change.

Understanding surface water–groundwater interactions for managing large irrigation schemes in the multi-country Fergana valley, Central Asia

Traditionally, surface water supplies are the sole sources to satisfy crop water requirements in large irrigation schemes such as those in the Fergana Valley, Central Asia. Recent studies indicate that 23–30% of these requirements are met from shallow groundwater, but this is not usually quantified. To manage favorable groundwater levels – i.e., without increasing soil salinity and nutrient leaching and reducing crop yields – information on, and quantification of, groundwater recharge and discharge rates at large spatial and temporal scales, as well as understanding their mechanisms of interaction, is indispensable. With the aim to quantify groundwater recharge, discharge and their interaction, a conceptual water balance model at a scale of a Water Consumers’ Association was established on a monthly basis for a 10-year period. Average groundwater recharge was estimated as 780 ± 75.7 mm, representing 62% of surface water supplies. The highest average annual recharge (930 mm) driven by excessive precipitation and water supply was in 2010 and the lowest (667–726 mm) was in years of lower water availability: 2006–2008 and 2012. The net groundwater recharge was 82.4 ± 79 mm, and determined the groundwater level fluctuations. The highest positive net groundwater recharge rate (247 mm) and the shallowest groundwater level (123 cm) also occurred in 2010. The negative net recharge in 2006 (–11 mm), 2008 (–41 mm) and 2012 (–5 mm) indicated deeper groundwater levels during these periods. The groundwater recharge values were excessively high even for this large irrigation scheme. To save limited freshwater resources, groundwater discharge should be reduced, with one option being to reduce excessive drainage outflow.

Groundwater Resources Assessment and Impact Analysis Using a Conceptual Water Balance Model and Time Series Data Analysis: Case of Decision Making Tool

The allocation of groundwater resources has been a challenge for many years due to its unforeseen side effect and lag time issues, which are often overlooked. The full impact of groundwater utilization/abstraction takes time to realize its effect at its full. In this paper, long-term effects and groundwater dynamics were assessed using a water balance model and a time series analysis, respectively. Undeveloped groundwater systems are commonly found in a state of equilibrium, where, on average, equal amounts of water are recharged and discharged. A water budget is a static accounting of the state of the system at a given time, often before the system is developed. Water balance analysis was carried out together with the groundwater through flow, hydrograph, and surface-groundwater interaction analysis (base flow index) to develop a conceptual water balance model, which is a very basic representation of a complex natural aquifer system and is instrumental to constrain and build a robust numerical model that can be readily justified and updated. A noble approach was employed to assess and constrain the discharge coming out of the model area to sustain the lake level, located to the north of the study area, using the whole lake catchment and lake water balance analysis. Based on the lake water balance, there is a deficit between input and output computation, and hence there should be a groundwater input to sustain the historical lake area. The analysis showed that the model area contributes 40% of the lake catchment, and hence the portion of the groundwater inflow feeding the lake was computed. This is one of the means to constrain the discharge, which adds more confidence to the recharge estimation. This is very important because the size of a sustainable groundwater development usually depends on how much of the discharge from the system can be captured by the development. Capture is independent of the recharge. Instead, it depends on the dynamic response of the aquifer system to the development. The idea that knowing the recharge is important in determining the size of a sustainable groundwater development is a myth and has no basis. The important entity in determining how a groundwater system reaches a new equilibrium is capture. How capture occurs in an aquifer system is a dynamic process. Following this study, lake water balance assessment was indirectly considered as prior information for the numerical model calibration of the discharge from the model area using a conductance parameter. Conductance is a key parameter to estimate the discharge volume together with the change in the simulated hydraulic head between time steps. The water balance error highlights which one is more sensitive, and this could help to assist in planning for future data collection/field work and where to invest the money. The water balance computation helps to figure out the degree of surface-groundwater interaction, uncertainty, sensitive parameter, helps in the decision to invest time and money, and operates as a cross check with other analytical or numerical modelling.

Variability analysis of hydrometeorological parameters under a climate change scenario in Northern Greece

In this work an attempt is undertaken to analyse the impacts of climate change in crucial hydrometeorological parameters affecting the agriculture production yield. As study area, the Siatista sub-basin of Aliakmon river was selected, located in Northern Greece. More particularly the regional hydrological cycle was evaluated on river basin spatial scale to assess regional impacts and variability. A monthly conceptual water balance model was calibrated, using historical hydrometeorological data covering a 30-year period. This model was applied to estimate runoff values at the outlet of the sub-basin incorporating the output data of a climate change scenario. The selected climate change scenario is United Kingdom Transient Run (UKTR) which is a transient scenario, referring to year 2080. The results show that the mean annual runoff, mean winter, as well as mean summer runoff values, will be reduced. The reduction ranges from 15% to 65%. The actual evapotranspiration in the winter months will increase (the range is from 6 to 800%), while the opposite occurs in the summer months (the range is from 38 to 69%) due to reduced runoff.

Estimating groundwater recharge for an arid karst system using a combined approach of time-lapse camera monitoring and water balance modelling

: Groundwater is the principal water resource in semi-arid and arid environments. Therefore, quantitative estimates of its replenishment rate are important for managing groundwater systems. In dry regions, karst outcrops often show enhanced recharge rates compared with other surface and sub-surface conditions. Areas with exposed karst features like sinkholes or open shafts allow point recharge, even from single rainfall events. Using the example of the As Sulb plateau in Saudi Arabia, this study introduces a cost-effective and robust method for recharge monitoring and modelling in karst outcrops. The measurement of discharge of a representative small catchment (4.0 middle dot 104 m2) into a sinkhole, and hence the direct recharge into the aquifer, was carried out with a time-lapse camera. During the monitoring period of two rainy seasons (autumn 2012 to spring 2014), four recharge events were recorded. Afterwards, recharge data as well as proxy data about the drying of the sediment cover are used to set up a conceptual water balance model. The model was run for 17 years (1971 to 1986 and 2012 to 2014). Simulation results show highly variable seasonal recharge-precipitation ratios between 0 and 0.27. In addition to the amount of seasonal precipitation, this ratio is influenced by the interannual distribution of rainfall events. Overall, an average annual groundwater recharge for the doline (sinkhole) catchment on As Sulb plateau of 5.1 mm has estimated for the simulation period. Copyright (C) 2015 John Wiley {\&} Sons, Ltd., (C) 2016 John Wiley {\&} Sons, Inc.

How would peak rainfall intensity affect runoff predictions using conceptual water balance models?

Abstract. Most hydrological models use continuous daily precipitation and potential evapotranspiration for streamflow estimation. With the projected increase in mean surface temperature, hydrological processes are set to intensify irrespective of the underlying changes to the mean precipitation. The effect of an increase in rainfall intensity on the long-term water balance is, however, not adequately accounted for in the commonly used hydrological models. This study follows from a previous comparative analysis of a non-stationary daily series of stream flow of a forested watershed (River Rimbaud) in the French Alps (area = 1.478 km2) (1966–2006). Non-stationarity in the recorded stream flow occurred as a result of a severe wild fire in 1990. Two daily models (AWBM and SimHyd) were initially calibrated for each of three distinct phases in relation to the well documented land disturbance. At the daily and monthly time scales, both models performed satisfactorily with the Nash–Sutcliffe coefficient of efficiency (NSE) varying from 0.77 to 0.92. When aggregated to the annual time scale, both models underestimated the flow by about 22% with a reduced NSE at about 0.71. Exploratory data analysis was undertaken to relate daily peak hourly rainfall intensity to the discrepancy between the observed and modelled daily runoff amount. Preliminary results show that the effect of peak hourly rainfall intensity on runoff prediction is insignificant, and model performance is unlikely to improve when peak daily precipitation is included. Trend analysis indicated that the large decrease of precipitation when daily precipitation amount exceeded 10–20 mm may have contributed greatly to the decrease in stream flow of this forested watershed.

Estimating water deficit and its uncertainties in water-scarce area using integrated modeling approach

Accurate assessment of water deficit and related uncertainties in water-scarce areas is strategically important in various fields of water resources management. This study developed a hybrid approach integrating conceptual water balance model and econometric regression to estimate water shortage and its related uncertainties in water-scarce areas. This hybrid approach was used to assess the agricultural water deficit of Beijing, an extremely water-scarce area in China. A predictive model of agricultural water demand was developed using the stepwise multiple regression method, and was validated by comparing the predicted values with observed data. Scenario analysis was employed to investigate the uncertainties of agricultural water shortage and agricultural water demand. This modeling approach can assist water administration in creating sustainable water allocation strategies in water-scarce areas.

Letter from editor

<div class="page" title="Page 1"><div class="section"><div class="layoutArea"><div class="column"><p>Welcome to Earth Sciences Research Journal, Volume 18, Number 1. More than 20 years have passed since we decided to be part of the scientific world in geology, seismology, geophysics, geodesy, meteorology, oceanography, planetary sciences, and so many other fields. We raised our voice to say to the world that in Colombia, there is a Journal committed to providing the highest level of manuscript in Earth Sciences.</p><p><span>It has been not an easy road, but we are here. This 2014 has been full of challenges moving us to find the best ways to present new manuscripts. Our Volume 18 was made possible by the non-profit cooperation of authors and reviewers working hand-in- </span><span>hand with us. </span></p><p><span>In this volume, we are presenting to the eyes of scientific world nine papers coming from three different continents, with contributions by people from seven countries. Our first paper comes from Egypt, about an aeromagnetic data analysis in the region of Fayoum-Cairo. This work regarding the October 12, 1992 earthquake, suggests how the new tectonics of Africa’s northeast is predominant in this area. From Turkey, our second manuscript obtained a new, important, more up-to-date and more reliable relationship between surface wave magnitude and rupture length for earthquakes in that country. The results obtained in this study will give some useful and up-to-date information to authors whose studies are focused in this area. </span></p><p><span>In the field of hydrogeology, the third article analyzes the hydrogeochemistry of shallow groundwater in the Yellow River alluvial plain. The results suggest that the shallow groundwater in the study area is fresh to moderately mineralized water. The assessment of samples shows how this water is acceptable for agricultural use but is not potable. From China, too, an interesting paper about the petrography and mineralogy of biotites within the Wushan granodiorite is presented. The formation conditions of these biotites are also determined and the significance of these minerals in terms of petrogenesis and mineralization is </span><span>discussed. </span></p><p><span>From India, where climate change is a topic trend, a study attempts to provide information on climate variability and its impacts on runoff in the Kosasthaliyar sub-basin. From Nigeria, a work related to aromatic biological markers are used for assessing thermal maturity of source rocks in the Campano-Maastrichtian Mamu formation. Results of this study show how these maturity values indicate that the coal and shale extracts are marginally mature for hydrocarbon generation. </span></p></div></div></div></div><div class="page" title="Page 2"><div class="layoutArea"><div class="column"><p><span>We invite you to read also three South American papers. From Colombia, the manuscripts titled “Enhancing time resolution by stabilized inverse filter and Q estimated on instantaneous spectra” and “Hydrocarbon Production Scenarios in Colombia. Review of Field Sizes, Hydrocarbon Reserves and Expectations of Conventional and Unconventional Resources” are presented. From Chile comes the paper “Uncertainty in rainfall input data in a conceptual water balance model: effects on outputs and implications for predictability”. </span></p><p><span>Thanks to every one of you and enjoy this issue of the ESRJ. </span></p></div></div></div>