Non-rainy Season Research Articles

Spatial-temporal pattern study on water conservation function using the SWAT model

AbstractThe performance of the water conservation function (WCF) affects the water supply and flood control capabilities of an ecosystem. In this study, we combined the water balance method with the Soil and Water Assessment Tool (SWAT) model to calculate the water conservation amount (WCA) upstream of the Xiong'an New Area (Zijingguan (ZJG), Zhongtangmei (ZJG) and Fuping (FP) basins) at annual and monthly scales from 2007 to 2017, and used multiple linear regression and geographic detector models to analyze the factors affecting the temporal changes and spatial pattern of the WCA. Our results reveal that the annual WCAs of the ZTM basin are all positive, while the WCAs of the ZJG and FP basins have negative values in drought years. The annual WCAs in the upstream of each basin have changed between positive and negative values. On the monthly scale, all areas of the ZJG, ZTM, and FP basins have positive and negative value changes of WCA between the rainy and non-rainy seasons. Precipitation, evapotranspiration, and their combined effects are the main factors leading to the temporal changes and spatial patterns of WCA in the study area. The above results can provide reference cases for other regions to carry out relevant research work.

The prevalence and seasonality of ruminant animal diseases in Ijebu-Ode, Ogun State, Nigeria.

A ten-year (1996-2005) record of treatment report on diagnosed ruminant diseases in Ijebu-Ode, Ogun State was evaluated to determine the prevalence and seasonality of the major ruminant diseases in the southwestern part of Nigeria. A total of 6880 ruminants comprising 114 cattle, 3312 sheep and 3454 goats were treated. Trypanomosis, Pneumonia, and Malnutrition showed seasonal fluctuation while Helminthiasis, Ectoparasitism, Gastro-Enteritis, Kata and Dystocia were distributed throughout the year. Helminthasis (3126 cases) had a seasonal occurrence of 31.99%, 31.54%, 11.89% and 29.01% for the hot-dry , hot-humid rainy, hot humid non-rainy and cool-humid rainy seasons respectively. During the hot-dry season, Trypanosomosis (19.29%) and malnutrition (3.51%) in cattle, Helminthiasis (14.31% and 11.87%) in sheep and goats respectively were the major problems. Ectoparasition (6.76% and 7.53%) and Kata (5.86% and 5.79%) in the sheep and goats respectively were the major problems during the hot-humid rainy season. Helminthiasis (3.51%) Gastro-Enteritis (3.51%) and Toxaemia/Septicaemia (3.51%) in cattle, Helminthiasis (4.23% and 5.91%), Ectoparasitism (2.60% and 1.74%) and Kata (3.02% and 2.72%) in sheep and goats respectively were the major problems during the hot-humid non-rainy season. Pneumonia (5.265) and Helminthasis (3.51%) in cattle, Helminthasis (13.90% and 11.60%), Kata (4.90% and 7.53%), Ectoparasitism (3.51% and 5.21%) and Pneumonia (2.42% and 1.80%) in sheep and goats respectively were the major diseases that occurred in the cool humid rainy season. The relevance of this report to effective control of measures for the ruminant enterprise in southwestern Nigeria is also highlighted.

Effect of Moisture Regimes on Water use Efficiency of Rabi / Summer Groundnut Genotypes in Northern Transition Zone of Karnataka

Background: During rabi / summer irrigation water is a scarce resource, but crop needs more water due to non-rainy season and warmer climate. Hence, a field experiment was conducted during rabi / summer season of 2016-17 to study the effect of irrigation water regimes on water use efficiency (WUE) of groundnut genotypes in Northern Transition Zone of Karnataka. Methods: This field study comprised of four main plots as water regimes viz. I1: (control) seven irrigations at 15 days interval from sowing to 105 DAS, I2: Stress at pegging stage; withdrawal of one irrigation between 45 - 60 DAS, I3: Stress at pegging and pod filling stage; withdrawal of two irrigations between 45-75 DAS, I4: Stress at pegging, pod filling and kernel development stage; withdrawal of four irrigations from 45-105 DAS and four genotypes as sub plots viz. G1: Dh-86, G2: Dh-101, G3: K-9 and G4: G2-52. Treatments were replicated thrice and laid out in split plot design. Result: Among the water regime, I2 recorded significantly higher WUE (6.2 kg ha-1 mm-1) followed by I1 (control; 5.5 kg ha-1 mm-1). Water regime I2 also recorded significantly higher pod yield and haulm yield (2,857 kg ha-1 4,648 kg ha-1, respectively) along with other yield attributes, but was found at par with control (I1). This study showed that WUE as well as yield of rabi / summer groundnut can be enhanced if crop was exposed only to mild stress by skipping an irrigation at pegging stage out of total seven irrigations. Among the genotypes, Dh-86 with 2,375 kg ha-1 of pod yield performed significantly better over others like Dh-101 (2,215 kg ha-1), K-9 (2,048 kg ha-1) and G2-52 (1,880kg ha-1) suggesting differential response to moisture stress, thus choice of moisture stress tolerant genotypes is equally important to enhance WUE. Interaction between irrigation regime and genotypes showed that Dh-86 (G1) with I2 irrigation regime recorded significantly higher WUE (6.9 kg ha-1 mm-1), pod yield (3,168 kg ha-1) and net return (Rs. 95,655 ha-1) and was found at par with full irrigation regime (I1).

Influence of seasonality on the physiological and seminal parameters of buffaloes in the western region of Pará1

ABSTRACT: Awareness of the physiological changes that occur when animals are subjected to climatic changes that are considered stressful is essential to maintain animal welfare and to be able to exploit their reproductive potential efficiently and rationally. The present study was carried out to evaluate climatic variables’ influence on physiological parameters, and Murrah buffalo ejaculates reared in a humid tropical climate in the Amazon. The immediate analyzes pertinent to the physical and morphological characteristics of the ejaculates were carried out and corresponded in the rainy season (RS) volume of 3.4±2.0mL; the mass activity of 4.4±0.5; motility of 80.4±5.6%; vigor of 4.4±0.4; concentration of 657,300±237,865.1 x 106sptz/mL; major defects of 9.0±2.6%; minor defects of 11.2±3.9%; total defects 20.2±5.3% and sperm plasma membrane integrity (SPMI) 84.8±5.6%, whereas in the non-rainy season (nRS), the results were 4.0±2.1mL; the mass activity of 3.0±1.0; motility of 56.2±13.4%; vigor of 3.0±1.0; concentration of 586,000±291,925.9 x 106sptz/mL; major defects of 20.8±9.9%; minor defects of 27.5±6.3%; total defects 48.3±9.3% and SPMI of 57.9±12.4%. Furthermore, a statistical difference (P<0.05) was observed for the parameters mass activity, motility, vigor, major defects, minor defects, total defects, and sperm plasma membrane integrity between both periods. The data on heart frequency, superficial temperature (head, back, groin, and scrotal pouch) showed a statistical difference between both periods (P<0.05). To conclude is necessary specific management in the non-rainy season that thermal stress is not a determining factor in reducing the reproductive quality of buffaloes; it is necessary to use means to improve animal welfare; one alternative is to use baths regularly for these animals or provide constant access to areas of rivers or lakes, as well as shading, preventing the buffaloes from being directly exposed to the unfavorable thermal environment.

Ectoparasitos ou suas lesões sugestivas em escolares de duas instituições da rede pública de um município do Nordeste brasileiro

RESUMO: As ectoparasitoses são frequentes em crianças em idade escolar e avaliar o status ectoparasitário torna-se relevante. Este estudo estabeleceu o status ectoparasitário dos escolares de ensino fundamental de 5 a 16 anos de idade, em duas instituições de ensino no município de União dos Palmares-AL, a partir da identificação in loco do ectoparasito ou de suas lesões sugestivas e de inquérito epidemiológico aos responsáveis. Foram avaliados 470 escolares em dois períodos diferentes (um período chuvoso e um período não chuvoso) para investigação da presença de lesão ou do próprio ectoparasito, pela inspeção corporal superficial (mãos, pés e cabelos). Entre os casos avaliados, observou-se ocorrência de 154 casos positivos, sendo 5% destes de Tunga penetrans, 65% Pediculus capitis e 30% Sarcoptes scabiei. A prevalência das ectoparasitoses foi de 21,3% para P. capitis, 10% para S. escabiei, e 1,5% para T. penetrans. Do total de casos positivos para alguma ectoparasitose, 41,5% (54/154) foram encontrados no período chuvoso e 23,4% (36/154) no período não chuvoso. Todos os casos positivos foram encaminhados ao tratamento. O estudo mostrou infestações para as principais ectoparasitoses, especialmente pediculose e escabiose, o que determina a grande importância dos ectoparasitos. Além disso, apesar de não existir períodos longos de estiagem na zona da mata alagoana, no período de escassez de chuvas, com altas temperaturas, característico da região, foi observada maior ocorrência para a pediculose, sendo determinada aqui a influência do período de coleta. 
 PALAVRAS-CHAVE: doenças parasitárias, ectoparasitoses, saúde pública.

Rainfall Event–Duration Thresholds for Landslide Occurrences in China

A rainfall threshold for landslide occurrence at a national scale in China has rarely been developed in the early warning system for landslides. Based on 771 landslide events that occurred in China during 1998–2017, four groups of rainfall thresholds at different quantile levels of the quantile regression for landslide occurrences in China are defined, which include the original rainfall event–duration (E–D) thresholds and normalized (the accumulated rainfall is normalized by mean annual precipitation) (EMAP–D) rainfall thresholds based on the merged rainfall and the Climate Prediction Center Morphing technique (CMORPH) rainfall products, respectively. Each group consists of four sub-thresholds in rainy season and non-rainy season, and both are divided into short duration (<48 h) and long duration (≥48 h). The results show that the slope of the regression line for the thresholds in the events with long durations is larger than that with short durations. In addition, the rainfall thresholds in the non-rainy season are generally lower than those in the rainy season. The E–D thresholds defined in this paper are generally lower than other thresholds in previous studies on a global scale, and a regional or national scale in China. This might be due to there being more landslide events used in this paper, as well as the combined effects of special geological environment, climate condition and human activities in China. Compared with the previous landslide model, the positive rates of the rainfall thresholds for landslides have increased by 16%–20%, 10%–17% and 20%–38% in the whole year, rainy season and non-rainy season, respectively.

Improved assessment of pasture availability in semi-arid grassland of South Africa.

Satellite remote sensing technology has been successfully used to monitor grassland productivity, especially for estimating the green component of biomass using popular indices such as Normalized Difference Vegetation Index (NDVI). The non-green component, which includes senescent and dead standing material, has not been widely quantified. Our study aimed at devising a satellite remote sensing-based method that can distinguish between green and non-green herbage, in order to improve the accuracy of total aboveground biomass (TBM) estimations. This in turn can minimise under-estimations of pasture availability in semi-arid grasslands. MODIS satellite data was used to determine the relations of various indices to ground-measured green aboveground biomass (GBM) and non-green aboveground biomass (NBM) in South African semi-arid grasslands. We found a strong correlation of GBM to NDVI. We were then able to detect a correlation of NBM to Normalized Difference Water Index (NDWI), but a robust relationship was between NDWI and the ratio of NBM to TBM. NDVI and NDWI were used to estimate long-term TBM, which varies inter- and intra-seasonally. During the non-rainy season, NBM is important to maintain livestock grazing and in this regard monitoring of pasture availability in terms of green and non-green herbage is critical for sustainable grassland management.

Assessment of Surface Water Resources of Eastern Iraq

Large amounts of runoff is generated in western Iran and flows into eastern Iraq due to relatively intensive rainstorms along the international border line. Currently, most of this runoff is being wasted by evaporation instead of being stored and preserved for later uses. This paper is an attempt to (1) assess and harness the water resources of eastern Iraq, and (2) propose a storage scheme to use the harvested water in the water shortage times. The runoff of eight catchment areas (Mandali, Qazania, Tursaq, Mirzabad, Galal Badra, al-Chabbab, al-Teeb, and Dwaireeg) is estimated using regression equations derived for areas in the western and southern parts of the United States of America. Several models were selected from two states based on catchment area location, average terrain elevation, average annual precipitation, and slope of main stream. Observed runoffs of Tursaq, Galal Badra, and al-Chabbab streams are analyzed using normal probability plots. Statistical analysis shows that there is no a statistically significant difference between observed and predicted runoffs for different return periods. The study proposes a water reservoir to be constructed within al-Shiwiaja Marsh to accommodate runoff generated within Mandali, Qazania, Tursaq, Mirzabad, and Galal Badra streams. The capacity of the proposed reservoir is 3000 Mm3 and the expected inflow from these streams is projected to exceed the capacity of the reservoir. The proposed reservoir will contribute to the flow of the River Tigris during the non-rainy seasons. More studies are needed to propose and design a storage scheme for two remaining streams (al-Teeb and Dwaireeg).

Effect of Environmental Factors on Variation Characteristics of Soil Microbial Respiration and Its Temperature Sensitivity

Studying the effect of environmental factors on the variation of soil microbial respiration and its temperature sensitivity (Q10) at different time scales under field conditions is of great significance for accurately understanding the region's climate warming potential. From March 2008 to November 2013, in situ soil microbial respiration rates were determined using an automated CO2 flux system (Li~8100) in long-term bare fallow soil at the Changwu State Key Agro-Ecosystem Experimental Station, Shaanxi, China, for studying the effect of environmental factors on the variation of soil microbial respiration and Q10 at different time scales. At diurnal time scales, the daily variation of soil microbial respiration rates showed a single-peak curve, which was closely related to soil temperature (P<0.05); whereas the daily mean soil microbial respiration rate and Q10 varied with soil moisture, with both showing the order of moderate soil moisture conditions > higher soil moisture conditions > lower soil moisture conditions[daily mean soil microbial respiration rate:1.20 μmol·(m2·s)-1 vs. 0.95 μmol·(m2·s)-1 vs. 0.79 μmol·(m2·s)-1; Q10:2.12 vs. 1.93 vs. 1.59]. At seasonal time scales, both the seasonal mean soil microbial respiration rate and Q10 showed the order of rainy season > non-rainy season[seasonal mean soil microbial respiration rate:1.11 μmol·(m2·s)-1vs. 0.90 μmol·(m2·s)-1; Q10:1.96 vs. 1.59], which was consistent with the trend of soil temperature and moisture (soil temperature:20.39 vs. 14.50℃; soil moisture:49.2% vs. 38.6%). The bivariate model of soil temperature and soil moisture could explain the greater seasonal variability of the soil microbial respiration rate than did the univariate model of soil temperature or soil moisture (R2:0.45-0.82 vs. 0.32-0.67 vs. 0.35-0.86; the fitting coefficient between the simulated and measured soil microbial respiration rates:0.76 vs. 0.64 vs. 0.58). At annual time scales, the annual cumulative soil microbial respiration ranged from 226 to 298 g·(m2·a)-1, with an average of 253 g·(m2·a)-1, and the annual Q10 ranged from 1.48 to 1.94, with an average of 1.70. The annual cumulative soil microbial respiration and Q10 showed a negative quadratic correlation with annual mean soil moisture (P<0.05), with the annual mean soil moisture explaining 39% and 54% of the annual variability of annual cumulative soil microbial respiration and Q10, respectively. In the bare soil treatment, the soil organic carbon decreased from 6.5 g·kg-1 at the beginning of the experiment to 5.5 g·kg-1 at present; whereas, the annual cumulative soil microbial respiration was up to 255 g·(m2·a)-1 and the loss of annual cumulative soil microbial respiration was 20 times larger than the loss of soil organic carbon in the Loess Plateau region, China.

Occurrence of Aflatoxin in Dairy Cow Feed Ingredients and Total Mixed Ration

Abstract. The level of aflatoxin B1 (AFB1) in dairy cow feed ingredients and Total Mixed Rations (TMRs) procured at two farms for low- and high-yielding dairy cows were surveyed. Raw milk from the two groups of cows at each farm was sampled 24 h after feeding the cows with examined feedstuffs during both the rainy and the non-rainy season. The aflatoxin M1 (AFM1) level in the raw milk samples was measured 12-24 h later. The levels of AFB1 in feed and AFM1 in milk were determined by validated enzyme linked immunosorbent assay (ELISA). The influence of farm management and type of feeding system on aflatoxin occurrence were considered. AFB1 and AFM1 were detected in 100% of feed and milk samples, respectively. The average level of AFB1 in the feed ingredients and TMRs were in the range of 1.6-104.7 µg/kg and 11.0-56.0 µg/kg, respectively. The average level of AFM1 in milk samples was 77.0 ng/L. The average concentrations of AFB1 in feeds and AFM1 in milk procured in the rainy season were significantly greater than those procured in the non-rainy season (p&amp;lt;0.05). Of the studied feed, maize silage was determined as the most contaminated feed ingredient in terms of AFB1 content. Furthermore, the AFM1 in 75% of milk samples obtained from high-yielding dairy cows and 25% of milk samples obtained from low-yielding dairy cows indicated AFM1 level higher than the maximum allowable Europe Commission limit of 50 ng/L. The results also showed that the occurrence of AFB1 in feed varied with farm feed management. The extent of translocation to AFMI in milk samples was dependent on type of cow, whether low- or high- milk yielding. This study suggests regular risk analysis and using good farm management practices are important to control aflatoxin contamination in feed and milk. Keywords: Aflatoxin B1, Aflatoxin M1, Dairy cows, Feed, Milk yield.

In-situ soil water dynamics under different irrigation methods in North East India

Availability of in-situ soil water plays a major role in exploiting the potential yield of crops under irrigated conditions. Depending on type of irrigation, variations of soil water is mostly observed at different soil depths within the root zone. The deviation of soil water at the edaphic zone becomes a deciding factor in assuring optimum yield. As availability of irrigation water is a great concern during non-rainy season, water saving irrigation techniques need to be adopted to maximize the productivity under hilly terrain. An experiment was laid out with potato as a test crop under the valley region of Meghalaya plateau on sandy clayey soil to study in-situ soil water dynamics under three different irrigation methods viz. furrow, micro-sprinkler and gravity-fed drip. Irrigation was scheduled at every weekly basis to restore back the soil water required to achieve the field capacity. Mean value of soil water up to 15 cm depth was 21.75, 22.65 and 23.45%, however, range (minimum to maximum) was 16.21-29.17; 15.56-29.21 and 17.84-28.97% for furrow, micro-sprinkler and gravity-fed drip irrigation, respectively. Co-efficient of variation was found to be the maximum (4.65%) for furrow over other two types of irrigations during the weekly interval. Deviation of in-situ soil water was found to vary rapidly at upper layer (30 cm) under furrow method of irrigation; but at deeper soil layer rapid variation was not observed. Water use efficiency of potato was evaluated to be 14.66, 18.78, 20.63 kg ha-1 mm-1 for furrow, micro-sprinkler and gravity-fed drip irrigation, respectively.

Characteristics of water and heat fluxes and its footprint climatology on farmland in low hilly region of red soil

The analysis of the characteristics and footprint climatology of farmland water and heat fluxes has great significance to strengthen regional climate resource management and improve the hydrothermal resource utilization in the region of red soil. Based on quality controlled data from large aperture scintillometer and automatic meteorological station in hilly region of red soil, this paper analyzed in detail the characteristics of farmland water and heat fluxes at different temporal scales and the corresponding source area distribution of flux measurement in the non-rainy season and crop growth period in hilly region of red soil. The results showed that the diurnal variation of water and heat fluxes showed a unimodal trend, but compared with the sunny day, the diurnal variation curves fluctuated more complicatedly on cloudy day. In the whole, either ten-day periods or month scale, the water and heat fluxes were greater in August than in September, while the net radiation flux was more distributed to latent heat exchange. The proportion of net radiation to latent heat flux decreased in September compared to August, but the sensible heat flux was vice versa. With combined effects of weather conditions (particularly wind), stability, and surface condition, the source areas of flux measurement at different temporal scales showed different distribution characteristics. Combined with the underlying surface crops, the source areas at different temporal scales also had different contribution sources.

Prevalence and Risk Factors of Cryptosporidium Infection in Children Hospitalized for Diarrhea in Guangzhou, China

This study was conducted to determine the prevalence, species and risk factors of Cryptosporidium infection in children hospitalized for diarrhea in Guangzhou region of China. A cross-sectional study was conducted to assess the prevalence and risk factors of Cryptosporidium infection in children (2 weeks to 10 years old) who were hospitalized for diarrhea. Cryptosporidium oocysts were detected using direct immunfluorescent assay and species were determined by sequencing a fragment (~800 bp) of the 18S rRNA gene. A questionnaire contains host, sociodemographic, family, hygiene, diet, zoonotic, and environmental risk factors was administered to patients to identify key factors associated with infections. The observed Cryptosporidium prevalence was 6.9% and the true prevalence was estimated to be 9.0%. Cryptosporidium infection was similar between male (7.4%) and female (6.1%) children and negatively associated with age (i.e., infection was more likely in younger children). Infections in children were significantly associated with family members’ diarrhea within past one month. Infection in children in suburban hospitals (7.8%) was significantly higher than that in urban hospitals (2.1%). The overall prevalence of Cryptosporidium in rainy season was significantly higher than that in non-rainy seasons. DNA sequences of the 18S rRNA gene from infected children were 99.12% to 100% identical to sequences in the GenBank of C. parvum isolates from humans and animals. Future works should determine the sources of zoonotic Cryptosporidium and routes of waterborne exposure in the rainy season in this region.

Climatological Comparison of Small- and Large-Current Cloud-to-Ground Lightning Flashes over Southern China

Abstract The first climatological comparison of small-current cloud-to-ground (SCCG; peak current ≤50 kA) and large-current cloud-to-ground (LCCG; peak current &amp;gt;50 kA, &amp;gt;75 kA, and &amp;gt;100 kA) lightning flashes is presented for southern China. The LCCG lightning exhibits an apparent preference to occur over the sea. The percentage of positive LCCG lightning during the nonrainy season was more than twice that during the rainy season, while the percentage of positive SCCG lightning showed small seasonal differences. Positive cloud-to-ground (PCG) lightning was more likely to feature a large peak current than was negative cloud-to-ground (NCG) lightning, especially during the nonrainy season and over land. Distinct geographical differences are found between SCCG and LCCG lightning densities and between their own positive and negative discharges. Furthermore, the percentages of positive lightning from LCCG and SCCG lightning exhibit distinctly different geographical and seasonal (rain and nonrainy season) distributions. The diurnal variations in SCCG and LCCG lightning are clearly different over the sea but similar over land. Diurnal variations in the percentage of positive lightning are functions of the peak current and underlying Earth’s surface. In combination with the University of Utah precipitation feature (PF) dataset, it is revealed that thunderstorms with relatively weak convection and large precipitation areas are more likely to produce the LCCG lightning, and the positive LCCG lightning is well correlated with mesoscale convective systems in the spatial distribution during nonrainy season.

Assessment of seasonal characteristics of streamflow droughts under semiarid conditions

Streamflow regime of semiarid environments is strongly influenced by rainy and non-rainy seasons, an indication that streamflow drought analysis should consider seasonality of streamflow behavior. The streamflow drought index (SDI), developed for continuous streamflow data, is modified to accommodate seasonal time series data. Possible SDI associations with standardized precipitation index are investigated at 3-, 6-, 9- and 12-month timescales. Case study area is semiarid Karkheh watershed (western Iran), with 42 years of data from selected rain gauge/hydrometric stations. Boxplots were used to establish rainy/non-rainy and wet/dry seasons from monthly data. According to Mann–Kendall test results, eight rain gauge and ten hydrometric stations indicated nonsignificant temporal trend, which were kept for further analysis. Markov chain results showed first-order dependency in all stations, indicating that drought predictability characteristics are based on the conditions of previous time period. Dry season streamflow droughts generally indicated longer durations compared to wet season droughts, and streamflow droughts were more persistent than meteorological droughts. According to results, historic drought of 1998–2001 has not recovered after more than a decade, indicating critical levels of SDI values during the dry season. Consideration of streamflow seasonality has been instrumental in detecting severe dry season droughts, not readily detectable when continuous time series data are used.

Distribution of nitrate and its implication for the contaminant source in groundwater of Huaibei Plain, Anhui Province

High concentration of NO3-N in groundwater can pose risk to human’s health, thus the study of NO3-N contamination in groundwater is a very important issue related to public health. Using a typical agriculture zone, Huaibei plain in Anhui Province of China as a field site, the temporal and spatial variation of groundwater NO3-N concentration was studied using a multivariate statistical factor analysis combined with Kaiser-Meyer-Olkin method based on a hydrogeological investigation from 2005 to 2009 year. The results show: (1) The contaminant in the groundwater of Huaibei Plain in Anhui Province are serious. 10% of the shallow groundwater samples in non-rainy season of 2005 exceeds the recommended value of NO3-N by Chinese drinking water standard (≥20 mg/L), while 17.5% exceeds the recommended value (11.3 mg/L) by EC. (2) About 15% of shallow groundwater in the whole study area was polluted in 2005 with the maximum of 97.67 mg/L; Groundwater NO3-N concentration is higher in non-rainy season than in rainy season. And the NO3-N content in groundwater shows the increasing trend at all three depths sampled from 2005 to 2009 year. (3) Groundwater nitrate pollution mainly derives from anthropogenic activities in Huaibei Plain, Anhui Province. Further quantitative analysis need to be studied in the future.

Evaluation of satellite precipitation retrievals and their potential utilities in hydrologic modeling over the Tibetan Plateau

Summary In this study, we evaluate four widely used global high-resolution satellite precipitation products against gauge observations over the Tibetan Plateau (TP). We also investigate the capability of the satellite products in streamflow simulations using the VIC hydrological model. Results show that the 3B42 and CMORPH perform better than the 3B42RT and PERSIANN at both plateau and basin scales. The 3B42RT and PERSIANN considerably overestimate the gauge precipitation estimates almost over the entire plateau, and the PERSIANN fail to capture the spatial and temporal pattern of the gauge precipitation estimates. For different satellite estimates, the error sources are systematically different for various seasons. For the 3B42, the miss bias is the main problem. The CMORPH exhibits obvious negative hit bias and miss bias in the rainy season and false-rain bias in the non-rainy season. The total bias in the 3B42RT and PERSIANN mainly attribute to positive hit bias in the rainy season and false-rain bias in the non-rainy season. The 3B42RT and PERSIANN show little capability for streamflow simulations over the TP, while the CMORPH exhibits an encouraging potential for hydrological applications in this regions in spite of the general underestimates. The 3B42 shows comparable performance to the CMA (China Meteorological Administration) data in both monthly and daily streamflow simulations mostly due to the monthly gauge adjustment involved in it.

Effect of nutrients on bioaccumulation of heavy metals in a tropical urban coastal lacustrine system.

The study on bioaccumulation of heavy metals in a lake reveals that during the nonrainy season, accumulation of cadmium in plankton is high in the upstream of the lake where anoxic freshwater condition exists resulting from inflow of urban wastes. Stern action is required to stop the bypass of sewage from the old sewer system especially in the commercial areas of Thiruvananthapuram city, either by augmenting the sewerage system or by treating sewage at the source. During monsoon season, the accumulation of heavy metals-namely lead and nickel, followed by cadmium and chromium-is high in phytoplankton resulting from high nitrate content caused by heavy rainfall. During postmonsoon, lead and nickel accumulation is high. The study emphasizes the need for stormwater management practices for the removal of lead in urban runoff from roads caused by vehicular exhaust, tire wear, and wastes from service stations and workshops.

Assessment of temporal hydrologic anomalies coupled with drought impact for a transboundary river flow regime: The Diyala watershed case study

Recent increases in human activities in shared river basins have unquestionably raised concerns about potential hydrological impacts, especially impacts of dams and large-scale water withdrawal schemes in the highlands. Anthropogenic pressures twinned with drought impacts have exacerbated water management challenges. This article assesses the cumulative consequences of upstream anthropogenic pressures and drought spells on temporal river flow regimes for the downstream country. The size and complexity of problems confronting transboundary river watersheds makes it necessary to use a representative example basin to study the problems and potential solutions. The Diyala (Sīrvān) river basin, which shares dozens of transboundary watersheds between Iraq and Iran, has been selected as a representative case study. A subset of the Indicators of Hydrologic Alteration (IHA) was utilised and climate variability was considered in assessing the combined effect of various forms of upstream human-river regulations and climatic conditions on natural flow regimes in the downstream state. Findings indicated that the anthropogenic river-regulation coupled with the impact of drought periods have noticeably modified the natural flow paradigm. The yearly average runoffs, which are no longer available for the downstream country, have soared to very high levels, particularly over the last fifteen years. More adverse impacts were detected in the non-rainy season. Findings reveal also that damming and considerable water diversion to large-scale irrigation projects in the upstream state are the main regulations affecting the management of shared water resources in the downstream country.

Investigation of spatio-temporal patterns of seasonal streamflow droughts in a semi-arid region

Spatio-temporal patterns of seasonal streamflow droughts were investigated for the semi-arid Karkheh watershed, located in western Iran with an area of 41,470 km2, exhibiting different rainfall regimes and topographical features. Streamflow seasonality was based on flow characteristics of rainy and non-rainy seasons. Data included 47–55 years of record from 10 selected hydrometric stations. Seasonal streamflow droughts were identified from streamflow drought characteristics (deficit volume, duration, intensity and statistical properties/distribution). Strong spatial pattern of summer droughts was detected for upper watershed region, based on station relative drought intensity distribution. Weak spatial pattern of winter droughts was detected in lower watershed, with extensions to parts of upper watershed. Temporal patterns of streamflow drought durations were not detected in the study area. For documented drought periods of 1960–1965 and 1998–2002, results showed spatial coherency in summer droughts among upper watershed stations, while winter droughts presented variable events of low intensity levels throughout the watershed. Results were verified using statistical testing and available documented literature. Probabilistic evaluations of extreme deficit volume and relative drought durations did not detect spatial/temporal patterns. Findings of this research, i.e., lack of temporal patterns and detection of strong summer spatial pattern are useful in regional drought mitigation planning.