Drainage Basin Research Articles

Ancient Egypt, Climate and the Nile: A Remark on the First Intermediate Period

The First Intermediate Period in ancient Egypt (22nd–21st centuries B.C.) is characterized by tomb “autobiographies” reporting on low Niles, famine and food donations from high officials and wealthy persons to the poor population after the collapse of the centralized monarchy. Egyptologists have expressed doubts that these sources reflect the real environmental and socio-political situation in Egypt at that date. In the 1970s B. Bell put forward a hypothesis about a severe and prolonged drought that struck in the late 3rd millennium B.C. the Middle East, including the Nile drainage basin; this led to a sharp drop of the Nile floods and, as a consequence (in Bell’s opinion), to the catastrophic decline of the Old Kingdom state. Egyptologists’ rejection of these theses and, in general, the interpretation of historical events of that era in the context of any environmental changes has recently acquired a particularly radical form, up to the revision of the most traditional Egyptological views on the First Intermediate Period, which is now even argued to have not been the time of the deepest crisis of the pharaonic civilization. Numerous independent scientifical studies, however, do not allow denying the important role of the natural factor at certain moments in the history of ancient Egypt, in particular, at the bifurcation between the Old and Middle Kingdoms. From the point of view of the socio-natural history, this was a socio-ecological crisis, a catastrophe that transformed qualitatively the systemic foundations of ancient Egyptian civilization at this stage of its evolution.

Geochemical modeling and hydrochemical analysis for water quality determination around mine drainage areas.

Water sources in mining areas do not retain their natural quality due to the influence of mine drainage. Water quality test was through hydrochemical analysis, speciation modeling, and saturation indices. Water samples were analyzed for pH, conductivity, nitrate, phosphate, sulfate, chlorite, sodium, magnesium, calcium, turbidity, total hardness, lead, zinc, iron, copper, cadmium, manganese, nickel, and chromium. Mean values of turbidity (0.13 mg/L), lead (0.01 mg/L), and cadmium (6.40 mg/L) exceeded their permissible values for potable water. Multivariate statistical analysis shows geogenic and anthropogenic sources of chemical species. Chemical speciation shows that the cations exist mostly in their soluble and mobile forms as free ions. Water quality index of 35-45.5 shows good water for drinking, irrigation, and industrial uses. The values of 63.8-68.8 and 103-121 reflect suitable water for industrial and irrigation uses. The research is integrated and credible in predicting groundwater pollutants to solve water pollution problems. PRACTITIONER POINTS: The mean value of turbidity, Pb, and Cd exceeded the WHO/NSDWQ standards for potable water. Correlation and principal component analyses show that the chemical species are from both geogenic and anthropogenic sources. Chemical speciation shows that the cations exist in their soluble and mobile forms as free ions except Cr. Saturation indices show that the minerals anhydrite, anglesite, vivianite, langite, larnakite, melanterite, and mirabilite are undersaturated in the water sources. Water quality index shows that the water is more suitable for irrigation than drinking and industrial uses.

Assessment of the Potential Flood Hazard of the Larbaâ Wadi, Rural Center of Sebt Boukellal, Taza, Morocco

Flood risk management often requires the use of geomorphological features to identify flood zones, and the use of hydraulic models to predict inundation dynamics and related impacts on the surrounding area. In this study, we used a hydraulic river simulation model to identify potential flood-prone zones on a small scale. It concentrated on a 2.5-kilometer section of the Larbaâ Wadi, which crosses the rural center of Sebt Boukellal. For estimating the peak discharge that occurs in the return periods of 10, 20, 50, and 100 years of the drainage area, we used the Rational method. Standard tables to estimate Manning’s coefficient and direct field measurements to feed the model. Model simulation has shown stability of the steady state, which witnesses the accuracy of the estimated and measured characteristics of the river system. During the calibration phase, we compared the model outputs to the observed floods and made adjustments to align the simulation with the field observations. Indeed, the 50-year flood remarkably matched the extent of the flood that occurred on September 27, 2000. The obtained results have shown that even for a 10year return period, the overflow affects properties within the floodplain. The 100-year flood exceeded the river’s capacity, causing water to spill onto the rural center’s streets and cultivated fields. The water level reached an elevation of 552.14 meters at Sebt Boukellal’s marketplace. These results were consistent with recent floods and confirm previous observations, indicating that the model precisely predicted the river’s behavior. The findings have shown that floods spanned large regions and suggested urgent intervention to protect lives and properties.

Mercury in the landscape components of the Don River Delta

The Don River Delta acts as a protective environmental barrier to the washout of pollutants from adjacent drainage areas. The priority pollutant is mercury, which comes as an industrial, agricultural and domestic wastewater`s part. The mercury concentrations levels in soils were determined by expeditionary and laboratory studies: the indicators ranged from 0,025 to 0,082 μg/g d.m. in the sandy-psammophyte meadow (section №1), in the sandy steppe (section №2) – from 0,012 to 0,022 μg/g d.m., in the true meadow (section №3) – from 0,027 to 0,4 μg/g d.m. and on the landscape with near-water vegetation (section №4) – from 0,035 to 0,565 μg/g d.m. The mercury accumulation in soils according to concentration coefficients is noted in the series «the Near-water landscape(13,5) > the True meadow landscape(5,9) > the Sandy-psammophyte meadow landscape(2,5) > the Sandy steppe landscape(1)». It was found that the soil moisture increased from the section №1 to the section №4 (on average from 18,06 to 35,4%), and the highest total biomass was recorded on the sandy-psammophyte landscape (46,55 t/ha) and the landscape with near-water vegetation (41,85 t/ha).

Application of Multivariate Statistical Methods for Determining Geochemical Trends of Elements on the Territory of Slovenia

The main objective of this study is to map multi-element geochemical anomalies in soil on a regional scale. We aimed to determine and evaluate the baseline geochemical values and main geochemical trends in soil that may serve as reference values against any future changes. A total of 817 topsoil samples (0–10 cm) were collected in a 5 × 5 km grid and analyzed for 35 elements using ICP-ES after multi-acid digestions (HClO4/HNO3/HCl/HF) and 53 elements using ICP-MS after modified aqua regia digestion (HCl/HNO3/H2O). The analytical results for the two different digestion methods (multi-acid digestion vs. aqua regia) were also compared for each chemical element. Multivariate statistical methods were applied to identify the geochemical trends and main sources of trace elements over the territory of Slovenia. Based on these results, seven natural and one mixed natural/anthropogenic geochemical association were established. The contents and trends of the determined factors are presented according to 8 natural units, 4 drainage areas, and geological units characteristic of Slovenia. The identified anthropogenic geochemical association combines toxic elements (Ag, Bi, Cd, Hg, P, Pb, S, Sn, and Zn). Increased values of these elements can be found in mining areas and metallurgic centers, in Quaternary sediments of the Sava River, and Adriatic Basin as the consequence of past mining activities and in the Julian Alps, where their origin could be connected to the atmospheric deposition.

Quantitative morphometric analysis of streams in extreme humid areas a case study of the Um-Mawiong river basin, Mawsynram, Meghalaya

Quantitative morphometric analysis of the drainage system is essential to characterising a watershed, as all the hydrologic and geomorphic processes occur within the watershed. Consequently, this plays a crucial role in understanding the geo-hydrological attributes of a drainage basin to the terrain feature and its flow patterns, thus enabling the estimate of the incidence of infiltration and runoff and other related hydrological characteristics of a watershed, which strongly impacts natural resource conservation. The study area selected is the Um-Mawiong River basin in Mawsynram, Meghalaya. The basin shows a dendritic pattern that highlights the homogeneity in the texture of the basin. Results suggest that the stream frequency of the basin is 19.10 km², suggesting a faster surface runoff and less infiltration. In addition, it has an Elongation ratio of 0.75 indicating an elongated basin shape. The current study demonstrates that the implementations of GIS techniques are trustworthy, efficient, and capable of managing extensive databases for managing river basins. The present study tries to analyse the linear, areal and relief aspects of the basin using a GIS environment and manipulated for different calculations. The analysis reveals that the total number of stream segments and length are maximum in first-order streams and decrease as stream order increases. The drainage density exhibits a high degree of positive correlation, i.e., 0.87, with its frequency suggesting an increase in stream population concerning increasing drainage density and vice versa.

Pulse power plasma stimulation: A technique for waterless fracturing, enhancing the near wellbore permeability, and increasing the EUR of unconventional reservoirs

The inherent characteristic of unconventional and ultra-low permeability reservoirs is a small drainage area that negatively affects the production rate and ultimate recovery (UR). Drilling horizontal wells, coupled with a stimulation process such as hydraulic fracturing, are applied to wells in these reservoirs to enhance well productivity. Although hydraulic fracturing has been the most famous stimulation technique in these reservoirs and has contributed to the increased US oil and gas production during the last several years, other stimulation techniques may be competitive with (or complementary to) hydraulic fracturing. This is because the main contribution to production in these reservoirs would be from complex fracture networks (often micro-cracks) combined with enhanced formation permeability rather than the classical two-wing fractures. Hence, a near-wellbore stimulation technique for improving the permeability of these reservoirs by activating the existing natural fractures and creating secondary microfractures would be highly desired. This paper investigates the pulse plasma stimulation technique to investigate such an approach of waterless stimulation/fracturing that creates multiple fractures and is also a permeability enhancement method. In this method, plasma is generated by discharging a high voltage and high current electrical energy in a very short time into two electrodes submerged in a wellbore filled with aqueous fluid. This study is divided into two sections. The first part presents experimental and numerical examples of stimulation/fracturing induced by pulse plasma in different rocks. Several parameters, including the effect of discharge with and without wire, input energy, confining stress, and rock type, on the induced fractures are studied. The second part uses the insights and results from the first part to numerically investigate pulse plasma's effects on production. Measurement of the formation permeability around the generated fractures indicated that the shock wave generated multiple fractures and increased the rock permeability by more than one or two orders of magnitude. The second part of the numerical section discusses the increased estimated rate and ultimate recovery (EUR) of horizontal wellbores due to fracturing and modified permeability resulting from pulse plasma. We present a sensitivity analysis on the magnitude and extent of the improved permeability region and its impact on EUR.

Distribution of regional lymph nodes metastasis in 870 cases of nasopharyngeal carcinoma and the suggestions for individualized elective prophylactic neck irradiation with intensity-modulated radiotherapy.

To explore the feasibility of individualized elective prophylactic neck irradiation (iEPNI) for optimizing current approach by investigating metastatic lymph nodes (LNs) distribution in nasopharyngeal carcinoma (NPC). Records of 870 NPC patients without distant metastasis in Hunan Cancer Hospital from January 2019 to December 2019 were reviewed. LNs' locations were identified based on the 2013 guidelines. The intra-regional lymphatic drainage (IRLD) areas included Station 1st (level VIIa and II), Station 2nd (level III and Va), and Station 3rd (level IV, Vb, and Vc). Other levels were categorized as extra-regional areas. Among the 870 patients, 94.5% cases exhibited LNs metastasis, including unilateral metastasis in 198 patients and bilateral metastasis in 624 patients. In the whole cohort, the most common involved IRLD areas were level IIb (87.1%), VIIa (80.0%), IIa (61.8%), Va (30.6%), IV (21.4%), Vb (8.9%), and Vc (1.1%). Besides, rates of LNs metastasis in Station 1st, 2nd, and 3rd were 94.3%, 61.1%, and 22.9%, respectively. Only four patients (4, 0.5%) revealed skipping metastasis among the three stations. Lymph node metastasis follows an organized pattern from Station 1st to 3rd with scarce skipping metastasis. A potential iEPNI strategy of prophylactic neck irradiation to the ipsilateral latter node-negative station appears promising in NPC patients. Further prospective investigations are warranted to validate the approach.

Estimation of Pollutant Load in Typical Drainage Ditches of Ningxia Yellow River Diversion Irrigation Area Based on LOADEST Statistical Model

To comprehensively comprehend the spatiotemporal variations in pollution load within the Sixth Drainage Ditch of the Ningxia Yellow River Diversion Irrigation Area, we employed the LOADEST model. We utilized daily flow data and concentrations of ammonia nitrogen (NH3-N), nitrate nitrogen (NO2-N), total nitrogen (TN), and total phosphorus (TP) to construct regression equations for the pollutant load at four distinct monitoring sections of the Sixth Drainage Ditch. The results unveiled an impressive range of correlation coefficients (R2) for the pollution load regression equations at the four monitoring sections, ranging from 72.42% to 94.4%. This indicates a strong fit for the pollution load regression equations, rendering them suitable for estimating the pollution load of the Sixth Drainage Ditch. Furthermore, the changing patterns of various pollutants in the same monitoring section exhibit a remarkable level of consistency. In each case, they initially experience an upward trajectory followed by a subsequent decrease. Notably, the total nitrogen (TN) load in the drainage area exceeds that of the total phosphorus (TP). The spatial distribution patterns of the total nitrogen (TN) and total phosphorus (TP) load within the Sixth Drainage Ditch exhibit a progressive increase from the upstream to downstream areas. Meanwhile, the spatial distribution characteristics of ammonia nitrogen (NH3-N) and nitrate nitrogen (NO2-N) follow a similar pattern of an initial increase followed by a decrease.

The impacts of rainfall and soil moisture to flood hazards in a humid mountainous catchment: a modeling investigation

Floods pose a significant threat to the safety of countries with severe societal, economic, and environmental consequences, especially the flash floods in mountainous regions. Previous studies have shown that many floods were caused by intense rainfall with highly saturated soil. In this study, we applied a physically-based distributed hydrological model (Integrated Hydrology Model, InHM) to a warm humid mountainous catchment in Southwest China, the Shouxi River. The main objective of our research is to investigate the relative importance of rainfall and antecedent soil moisture on flood generation in our study region. Our results show that an increase in rainfall return period and antecedent soil saturation ratio significantly increased peak flow and shortened peak time. There is a correlation between the ratio of antecedent soil saturation ratio to rainfall (SPR) and peak flow. When SPR <1, there is a positive correlation; when SPR >1, there is a negative correlation. Additionally, with the increase in drainage area, the relative importance of rainfall tends to decrease, while the relative contribution of soil saturation ratio tends to increase. The findings could provide support for the determination of the dominant factors influencing runoff generation in humid regions, offering scientific support for the timely and effective flood prevention and mitigation measures in mountainous regions.

Urban Stormwater Quality in Arequipa, Southern Peru: An Initial Assessment

Urban stormwater quality has been sampled and chemically analyzed in the city of Arequipa, southern Peru. Stormwater samples generated from a 0.04 km2 drainage area in a downtown location were collected during two rainy seasons (2022 and 2023), including both first flush and peak flow for each storm event, analyzing physical and chemical (metals) variables. Results were compared with Peruvian agricultural irrigation standards, identifying also temporal changes and statistical correlations. Several metals (B, Cu, Fe, Mn, and Zn) were detected at concentrations above Peruvian MPLs, with B being the analyte that violated the norm more often. Most pollution occurred at the beginning of each rainy season and during the first flush stages. All vehicle-related contaminants were well correlated except for Pb and Se, which were assumed to have a different source of origin. We recommend that further investigations should focus on the effects of urban stormwater on downstream ecosystems in Peru. Similarly, we strongly recommend the creation of new regulations that ensure proper stormwater quality released from urban areas of this country, as well as preventive/treatment practices to minimize the pollution of downstream aquatic ecosystems and ensure healthy water to irrigate crops located downstream from cities.

TECHNICAL AND ECONOMIC ASPECTS OF THE IMPLEMENTATION OF WATER REMOVAL TARIFFS ON DRAINED LANDS OF UKRAINE

The article highlights the main provisions of setting tariffs for water removal services for drainage. The application of tariffs is considered as an economic tool for increasing the efficiency of the use of drained lands when implementing the Strategy of Irrigation and Drainage in Ukraine [1]. An analysis of the provisions of the Law of Ukraine "On the Organization of Water Users and Stimulation of Hydrotechnical Land Reclamation"[2] regarding the provision of water users with water removal services for drainage by water user organizations and the payment of services by water users by the established water removal tariff was carried out. Emphasis is placed on the priority of the efforts in the field of hydraulic reclamation, namely proper operation and restoration of the country's drainage systems. The main point of the study is to realize the role of the status of water users who use water bodies to meet the needs of agriculture. According to the current legislation of Ukraine, the methodology of tariff formation should be based on a single basis - both for water supply and water removal.
 It is necessary to take into account the requirements of EU regulations regarding the consideration of the activities specifics in the field of water policy. Information on the development of water user organizations in Ukraine is provided and the operation costs of reclamation infrastructure facilities on the country's drainage systems are analyzed. The practice of foreign countries regarding the application of tariffs for water removal is given and the factors of the natural environment that were taken into account when selecting the option/options of water management in agriculture on drained lands of the country are outlined. The vision of researchers regarding the method of establishing and applying tariffs is given and a thorough assessment of the reasoning of scientists is provided. The areas for further research in the field of tariff formation for drainage are indicated. The base of tariff formation and methodical approaches to the formation of tariffs for water removal in the drainage area in Ukraine are proposed. The normative legal acts of Ukraine, the UN, EU bodies, the World Bank, data from scientific studies on tariff formation in agriculture on drained lands for 1991-2023, and administrative data were used as the main sources of information for the article.

Antimony(V) behavior during the Fe(II)-induced transformation of Sb(V)-bearing natural multicomponent secondary iron mineral under acidic conditions

Fe(II)-induced phase transformations of secondary iron minerals have attracted considerable attention due to their influence on antimony (Sb) mobility. However, Fe(II)-induced natural multicomponent secondary iron mineral (nmSIM) transformations and the corresponding repartitioning of Sb on nmSIM under acidic conditions upon Fe(II) exposure have not been systematically examined. Herein, we investigated the effect of Fe(II) on nmSIM mineralogy and Sb mobility in Sb(V)-bearing nmSIM at pH 3.8 and 5.6 at various Fe(II) concentrations over 15 d. The Sb(V)-bearing nmSIM phase transformation occurred under both strongly and weakly acidic conditions without Fe(II) exposure, while the presence of Fe(II) significantly intensified the transformation, and substantial amounts of intermediary minerals, including jarosite, ferrihydrite, lepidocrocite and fougerite, formed during the initial reaction stage, especially at pH 5.6. X-ray diffraction (XRD) analyses confirmed that goethite and hematite were the primary final-stage transformation products of Sb(V)-bearing nmSIM, regardless of Fe(II) exposure. Throughout the Sb(V)-bearing nmSIM transformation at pH 3.8, Sb release was inversely related to the Fe(II) concentration in the initial stage, and after maximum release was achieved, Sb was gradually repartitioned onto the nmSIM. No Sb repartitioning occurred in the absence of Fe(II) at pH 5.6, but the introduction of Fe(II) suppressed Sb release and improved Sb repartitioning on nmSIM. This transformation was conducive to Sb reimmobilization on Sb(V)-bearing nmSIM due to the structural incorporation of Sb into the highly crystalline goethite and hematite generated by the Sb(V)-bearing nmSIM transformation, and no reduction of Sb(V) occurred. These results imply that Fe(II) can trigger mineralogical changes in Sb(V)-bearing nmSIM and have important impacts on Sb partitioning under acidic conditions. These new insights are essential for assessing the mobility and availability of Sb in acid mine drainage areas.

Relationship between annual soil erosion and surface runoff in Wadi Hanifa sub-basins

Abstract Soil erosion is the major environmental risk that causes topsoil loss, which decreases fertility in agricultural land. Spatial estimation of soil erosion is essential for conserving land resources and for developing control plans. This study evaluated soil erosion in 17 sub-basins of the Wadi Hanifa catchment using the Gavrilović model. The soil erosion rate is categorized into three classes based on the annual volume of rainfall and runoff. About 21% of the drainage area of Wadi Hanifa is affected by erosion severity, and 33% of the area is affected by severe erosion. The correlation obtained between the annual soil erosion and annual volumes of rainfall and runoff is significant. It is concluded from the results that the drainage area of the north-western part suffers from a high soil erosion risk. The NRCS-CN and erosion predict that the Gavrilović model can be applied for estimating and analyzing the spatial distribution of soil erosion over more drainage watersheds in Saudi Arabia. Now, the GIS techniques are one of the best tools for developing the conservation and management planning processes of soil resources.

Can the Accuracy of Fine-Resolution Precipitation Products Be Assessed from the Surrounding Water Balance and Drought Chain (WBDC) in the Qinghai–Tibetan Plateau?

The Qinghai–Tibetan Plateau (QTP), which has a unique and severe environment, suffers from the absence of rainfall gauges in western arid land. Using different precipitation products in this region would easily lead to contradictory results. To evaluate nine fine-resolution precipitation products in the QTP, we propose a “down to top” methodology, based on water balance and drought chain, by forecasting two accuracy assessment indices—multi-year precipitation bias and precipitation correlation. We assessed the biases of all products in the Jinsha–Yalong, Yellow, Heihe, Yangtze, Yarlung Zangbo catchments and interior drainage areas. And we assessed gauge-based correlation of precipitation products, based on the correlations between precipitation product-based effective drought index (EDI), Soil Moisture Active Passive (SMAP)-based soil moisture anomaly, and the moderate-resolution imaging spectroradiometer (MODIS)-based normalized difference vegetation index (NDVI) anomaly (R = 0.712, R = 0.36, and R = 0.785, respectively) for cross-sectional rainfall observations on the Tibetan Plateau in 2018. The results showed that ERA5-Land and IMERG merged precipitation dataset (EIMD) can efficiently close the water budget at the catchment scale. Moreover, the EIMD-based EDI exhibited the best performance in correlation with both the SMAP-based soil moisture anomaly and MODIS-based NDVI anomaly for the three main herbaceous species areas—Kobresia pygmaea meadow, Stipa purpurea steppe, and Carex moorcroftii steppe. Overall, we find that EIMD is the most accurate among the nine products. The annual average precipitation (2001–2018) was determined to be 568.16 mm in the QTP. Our assessment methodology has a remote sensing basis with low cost and can be used for other arid lands in the future.

Differentiating between point and non-point source nutrient loadings of wastewater in an agriculturally impacted area using a hybrid statistical model

Nutrient contamination from point and non-point sources can lead to harmful consequences, such as algal blooms. Point and non-point nutrient loading estimation is determined using modeling approaches and often require an abundance of variables and observations for calibration. Small rural streams that lack water use designations often lack available data to utilize current modeling strategies. This study proposes the use of a 3-phase hybrid stepwise statistical modeling approach using generalized linear mixed models (GLMM) and a reference stream. Two streams in Central Texas were sampled for 13 months between February 2020 and February 2021, one being impacted by a wastewater treatment plant (WWTP). Dissolved phosphorus (PO4-P), ammonia (NH3-N), nitrite/nitrate (NO2 + NO3-N), total nitrogen (TN), and total phosphorus (TP) were sampled in both streams for each month. Non-point sources of contamination, such as land use/land cover and geomorphology composition, were quantified for both sub-basin drainage areas. Phase I models predicted nutrient concentrations in the reference stream using non-point source variables along with discharge and temporal variables. Best fit models were carried forward to phase II and leveraged a point-source variable, which is a naïve estimate of effluent nutrient concentration in the absence of assimilation. Phase II model coefficients highlight the significance of point-source contamination in predicting nutrient concentration, but overall lacked the ability to make future predictions under new hydrologic regimes from WWTP intensification. Phase III models included deterministically calculating an uptake variable using the relationship between discharge and wetted widths, predicting background non-point concentrations by leveraging phase I models, and calculating future nutrient loadings from WWTP intensification. This approach predicted significant increases in nutrient concentrations under planned WWTP intensification scenarios and decreased uptake efficiencies under the new hydrologic regimes.

Estimating Sediment Yield at Sungai Pusu Watershed using Soil and Water Assessment Tool (SWAT) Model

Sediment yield is the net result of soil erosion and sediment deposition processes. In the watershed, sediment yields are dominantly determined by stream flow, drainage area, and channel size. Land-use activity conducted by human is one of the major contributions to the sediment yield in the watershed. The study area covered in this study is the Sungai Pusu which flows through International Islamic University Malaysia (IIUM). Significant amount of sediments is deposited in Sungai Pusu due to the improper land clearing activities that are taking place along the river’s main tributaries. As a result, the water quality of Sungai Pusu is rapidly deteriorating. Sediment yield estimation is crucial in order to design suitable measure to rehabilitate the river. The aim of this study is to estimate sediment yield at Sungai Pusu watershed using SWAT model. Remote sensing and Geographic Information System (GIS) were used to evaluate sedimentation over time in the Sungai Pusu watershed. The SWAT model was performed to simulate water balance, stream flow, and sediment yield. The annual sediment yield obtained by the model is 427-ton ha-1 year-1.

Variability in sediment particle size, mineralogy, and Fe mode of occurrence across dust-source inland drainage basins: the case of the lower Drâa Valley, Morocco

Abstract. The effects of desert dust upon climate and ecosystems depend strongly on its particle size and size-resolved mineralogical composition. However, there is very limited quantitative knowledge on the particle size and composition of the parent sediments along with their variability within dust-source regions, particularly in dust emission hotspots. The lower Drâa Valley, an inland drainage basin and dust hotspot region located in the Moroccan Sahara, was chosen for a comprehensive analysis of sediment particle size and mineralogy. Different sediment type samples (n= 42) were collected, including paleo-sediments, paved surfaces, crusts, and dunes, and analysed for particle-size distribution (minimally and fully dispersed samples) and mineralogy. Furthermore, Fe sequential wet extraction was carried out to characterise the modes of occurrence of Fe, including Fe in Fe (oxyhydr)oxides, mainly from goethite and hematite, which are key to dust radiative effects; the poorly crystalline pool of Fe (readily exchangeable ionic Fe and Fe in nano-Fe oxides), relevant to dust impacts upon ocean biogeochemistry; and structural Fe. Results yield a conceptual model where both particle size and mineralogy are segregated by transport and deposition of sediments during runoff of water across the basin and by the precipitation of salts, which causes a sedimentary fractionation. The proportion of coarser particles enriched in quartz is higher in the highlands, while that of finer particles rich in clay, carbonates, and Fe oxides is higher in the lowland dust emission hotspots. There, when water ponds and evaporates, secondary carbonates and salts precipitate, and the clays are enriched in readily exchangeable ionic Fe, due to sorption of dissolved Fe by illite. The results differ from currently available mineralogical atlases and highlight the need for observationally constrained global high-resolution mineralogical data for mineral-speciated dust modelling. The dataset obtained represents an important resource for future evaluation of surface mineralogy retrievals from spaceborne spectroscopy.

A comprehensive analysis of transient rate and rate derivative data of an oil well intercepted by infinite-conductivity hydraulic fracture in closed systems

This paper presents a method for analyzing constant-pressure drawdown test of infinite-conductivity fractured wells in bounded reservoirs. The presented method is based on the Tiab direct synthesis approach. The fracture and reservoir parameters are directly determined from the rate and rate derivative of the well test data. New equations describing the elliptical flow regime and the transition from the pseudoradial regime to the boundary-dominated regime of different rectangular reservoirs are also presented. The various flow regimes occurring during the well test are easily identified based on the shape of the plotted data and the slope of each flow regime. The unique features of the slopes of the various regimes and their intersection points are utilized to determine the fracture half-length, formation permeability, skin factor, well drainage area, and reservoir shape factor. Moreover, new equations defining the intersection points of the straight lines corresponding to different flow regimes are presented. These equations are very important for confirming the precision of the calculated results. A systematic process demonstrating the application of the proposed method to linear, elliptical, pseudoradial, and boundary-dominated regimes is well delineated. Comprehensive examples are presented to validate the efficiency of the proposed technique. The examples show that even if some of the flow regimes are not fully developed, the method can still be used to determine the formation and fracture properties using information obtained from the remaining flow regimes. This is one of several advantages of the proposed technique over conventional techniques.

A new distinctively striped species of bushynose catfish (Siluriformes: Loricariidae: Ancistrus) from the Pachitea River drainage, Pasco, Peru.

With 76 currently valid species, the bushynose catfish genus Ancistrus is the fourth most species-rich catfish genus, yet Ancistrus diversity remains underestimated, with many species still undescribed. This is especially true of the Peruvian Andean headwaters of the Amazon, which are rich in unnamed Ancistrus species but have received little recent taxonomic attention. We describe a distinctively striped new Ancistrus species from tributaries of the Palcazú River, in the Pachitea-Ucayali-Amazonas drainage basin. The new species differs from all congeners by having black, vermiculated lines covering the head and two to four distinct black, parallel, lateral body stripes from head to caudal fin (vs. body uniformly colored or with dark or light spots or blotches over head and body, or black vermiculate lines on flanks). The new species is the fifth valid species of Ancistrus described from the rich Ucayali River ichthyofauna. It has previously been recognized in the aquarium fish trade as L267.