Risk assessment of maize drought disaster in southwest China using the Environmental Policy Integrated Climate model

The East Asian monsoon has a tremendous impact on agricultural production in China. An assessment of the risk of drought disaster in maize-producing regions is therefore important in ensuring a reduction in such disasters and an increase in food security. A risk assessment model, EPIC(Environmental Policy Integrated Climate) model, for maize drought disasters based on the Erosion Productivity Impact Calculator crop model is proposed for areas with the topographic characteristics of the mountainous karst region in southwest China. This region has one of the highest levels of environmental degradation in China. The results showed that the hazard risk level for the maize zone of southwest China is generally high. Most hazard index values were between 0.4 and 0.5,accounting for 47.32% of total study area. However,the risk level for drought loss was low. Most of the loss rate was 0.1, accounting for 96.24% of the total study area. The three high-risk areas were mainlydistributed in the parallel ridge–valley areas in the east of Sichuan Province, the West Mountain area of Guizhou Province, and the south of Yunnan Province.These results provide a scientific basis and support for the reduction of agricultural drought disasters and an increase in food security in the southwest China maize zone.     

Isotopic analysis to quantify the role of the Indian monsoon on water resources of selected river basins in the Himalayas

Western disturbances (WDs) and Indian summer monsoon (ISM) led precipitation play a central role in the Himalayan water budget. Estimating their contributions to water resource is although a challenging but essential for hydrologic understanding and effective water resource management. In this study, we used stable water isotope data of precipitation and surface waters to estimate the contribution of ISM and WDs to the water resources in three mountainous river basins - Indus, Bhagirathi and Teesta river basins of western, central and Eastern Himalayas. The study reveals distinct seasonality in isotope characteristics of precipitation and surface waters in each river basin is due to changes in moisture source, hydrometeorology and relief. Despite steady spatial variance in the slope and intercept of regression lines from the Teesta to Indus and the Bhagirathi river basins, the slope and intercept are close to the global meteoric water line and reported local meteoric water line of other regions in the Himalayas and the Tibetan Plateau. The two-component end-member mixing method using d-excess as tracer were used to estimate the contribution from ISM and WD led precipitation to surface water in aforementioned river basins. The results suggest that the influence of the ISM on the water resources is high (>72% to annual river flow) in Teesta river basin (eastern Himalayas), while as the WDs led precipitation is dominantly contributing (>70% average annual river flow) to the surface waters in the Indus river basin (western Himalayas). The contribution of ISM and WD led precipitation in Bhagirathi river basin is 60% and 40%, respectively. The findings demonstrate that the unusual changes in the ISM and WD moisture dynamics have the potential to affect the economy and food security of the region, which is dependent on the availability of water resources. The obtained results are of assistance to policy makers/mangers to make use of the information for better understanding hydrologic response amid unusual behaviour of the dual monsoon system over the region.     

Metals removal during estuarine mixing of Arvand River water with the Persian Gulf water

In the present study, the removal of dissolved and colloidal Cd, Co, Cu, Ni and Zn in Arvand River water during estuarine mixing with the Persian Gulf water is investigated. The flocculation process was investigated for a series of mixtures with salinities ranging from 0.48 to 30.3^. The flocculation rates were indicative of the non-conservative behavior of studied metals during estuarine mixing. Rapid flocculation in the low salinity regimes was observed. The order of the final flocculation rate of metals in the river water was as follows: Co (91.2%)> Cd (86.9%)> Zn (83%)> Cu (75.2%)> Ni (74.3%). Salinity, pH, EC and dissolved oxygen do not govern the flocculation of metals during estuarine mixing. The results of the present investigation show that estuarine processes can be considered as an effective mechanism in self purification of colloidal metals that are anthropogenically introduced into the fresh water ecosystem.     

Multi-factor impact analysis of agricultural production in Bangladesh with climate change

Diverse vulnerabilities of Bangladesh's agricultural sector in 16 sub-regions are assessed using experiments designed to investigate climate impact factors in isolation and in combination. Climate information from a suite of global climate models (GCMs) is used to drive models assessing the agricultural impact of changes in temperature, precipitation, carbon dioxide concentrations, river floods, and sea level rise for the 2040–2069 period in comparison to a historical baseline. Using the multi-factor impacts analysis framework developed in Yu et al. (2010), this study provides new sub-regional vulnerability analyses and quantifies key uncertainties in climate and production. Rice (aman, boro, and aus seasons) and wheat production are simulated in each sub-region using the biophysical Crop Environment REsource Synthesis (CERES) models. These simulations are then combined with the MIKE BASIN hydrologic model for river floods in the Ganges-Brahmaputra-Meghna (GBM) Basins, and the MIKE21 Two-Dimensional Estuary Model to determine coastal inundation under conditions of higher mean sea level. The impacts of each factor depend on GCM configurations, emissions pathways, sub-regions, and particular seasons and crops. Temperature increases generally reduce production across all scenarios. Precipitation changes can have either a positive or a negative impact, with a high degree of uncertainty across GCMs. Carbon dioxide impacts on crop production are positive and depend on the emissions pathway. Increasing river flood areas reduce production in affected sub-regions. Precipitation uncertainties from different GCMs and emissions scenarios are reduced when integrated across the large GBM Basins’ hydrology. Agriculture in Southern Bangladesh is severely affected by sea level rise even when cyclonic surges are not fully considered, with impacts increasing under the higher emissions scenario.     

Unique first-forbidden β-decay rates for neutron-rich nickel isotopes in stellar environment

In astrophysical environments, allowed Gamow-Teller (GT) transitions are important, particularly for β-decay rates in presupernova evolution of massive stars, since they contribute to the fine-tuning of the lepton-to-baryon content of the stellar matter prior to and during the collapse of a heavy star. In environments where GT transitions are unfavored, first-forbidden transitions become important especially in medium heavy and heavy nuclei. Particularly in case of neutron-rich nuclei, first-forbidden transitions are favored primarily due to the phase-space amplification for these transitions. In this work the total β-decay half-lives and the unique first-forbidden (U1F) β-decay rates for a number of neutron-rich nickel isotopes, ^72–78Ni, are calculated using the proton-neutron quasi-particle random phase approximation (pn-QRPA) theory in stellar environment for the first time. For the calculation of the β-decay half-lives both allowed and unique first-forbidden transitions were considered. Comparison of the total half-lives is made with measurements and other theoretical calculations where it was found that the pn-QRPA results are in better agreement with experiments and at the same time are suggestive of inclusion of rank 0 and rank 1 operators in first-forbidden rates for still better results.     

Study of Gamow–Teller transitions in isotopes of titanium within the quasi particle random phase approximation

The Gamow–Teller (GT) transition is inarguably one of the most important nuclear weak transitions of the spin-isospin στ type. It has many applications in nuclear and astrophysics. These include, but are not limited to, r-process β-decays, stellar electron captures, neutrino cooling rates, neutrino absorption and inelastic scattering on nuclei. The quasiparticle random phase approximation (QRPA) is an efficient way to generate GT strength distribution. In order to better understand both theoretical systematics and uncertainties, we compare the GT strength distributions, centroid and width calculations for \({^{40\mbox{--}60}\mathrm{Ti}}\) isotopes, using the pn-QRPA, Pyatov method (PM) and the Schematic model (SM). The pn-QRPA and SM are further sub-divided into three categories in order to highlight the role of particle-particle (pp) force and deformation of the nucleus in the GT strength calculations. In PM, we study only the influence of the pp force in the calculation. We also compare with experimental results and other calculations where available. We found that the inclusion of pp force and deformation significantly improves the performance of SM and pn-QRPA models. Incorporation of pp force leads to pinning down the centroid value in the PM. The calculated GT strength functions using the pn-QRPA (C) and SM (C) models are in reasonable agreement with measured data.     

High-intensity precipitation measurement using remote methods

Considered is a case of the cumulonimbus cloud development in the southwestern part of Saudi Arabia with a very high precipitation intensity. The height of the cloud top amounted to 14 km and the radar reflectivity, to 60 dBZ. Carried out is the comparison of remote methods of measuring the intensity of precipitation from the cloud under study: the radar (using the relationship between the reflectivity and precipitation intensity) and satellite IR-radiometric (based on the results of sounding with the SEVERI radiometer installed at the Meteosat-8 satellite) methods. A split-window technique was used for detecting the position of the cloud top from the radiometric observations. The analysis enabled to select the best relationships for estimating the precipitation intensity from the data of radar and satellite measurements. The computations based on these relationships correspond most closely to the ground-based measurements with the precipitation gage.     

一次引发南亚大暴雨的季风低压结构、涡度与水汽收支分析

对2003年夏季风期间,7月24～28日印度季风槽内季风低压发展西移与阿拉伯海中尺度低压合并引发南亚的一次大暴雨过程进行了诊断分析,探讨了印度季风槽、季风低压的三维结构以及低压区域的涡度、水汽收支.揭示和确认了一些事实:1)印度季风槽区对流层中下层存在明显的风场切变,槽区高温高湿,为单一性质的热带气团,低层为对流不稳定,槽区对应正涡度区;2)季风低压是一较深厚系统.动力结构为低层正涡度,高层负涡度,低层辐合,高层辐散.其西移速度约500 km·d.季风低压北侧整层为深厚的东风,南侧在对流层中低层为西风,在高层为东风.热力结构在低层(700～800 hPa)间存在弱冷区,而中高层几乎为暖心结构.低压对应高湿区,低压中心西侧整层为相对湿度大值区;3)季风低压的发展过程中,低层的辐合场制造正涡度,促进低压的发展;4)低压区水汽强烈辐合,西边界输入量最大.在此研究工作的基础上,作者还比较了夏季风期间南亚印度季风槽和东亚梅雨锋系统的异同.     

Geochemical,isotopic and hydrological mass balance approaches to constrain the lake water–groundwater interaction in Dal Lake,Kashmir Valley

It is important to have qualitative as well as quantitative understanding of the hydraulic exchange between lake and groundwater for effective water resource management. Dal, a famous urban fresh water lake, plays a fundamental role in social, cultural and economic dynamics of the Kashmir Valley. In this paper geochemical, isotopic and hydrological mass balance approaches are used to constrain the lake water–groundwater interaction of Dal Lake and to identify the sources of lake water. Water samples of precipitation (n = 27), lake water (n = 18) and groundwater (n = 32) were collected across the lake and its catchment for the analysis of δ¹⁸O and δ²H. A total of 444 lake water samples and 440 groundwater samples (springs, tube wells and dug wells) were collected for the analysis of Ca²⁺, Mg²⁺, HCO₃ ^?, SO₄ ^2?, Cl^?, NO₃ ^?, Na⁺ and K⁺. Water table and lake water level were monitored at 40 observation locations in the catchment. Water table map including pH and EC values corroborate and verify the gaining nature of the Dal Lake. Stable isotopes of lake water in Boddal and Gagribal basins showed more deviation from the global meteoric water line than Hazratbal and Nigeen basins, indicating the evaporation of lake water. The isotopic and geochemical mass balance suggested that groundwater contributes a significant proportion (23–40%) to Dal Lake. The estimated average groundwater contribution to Dal Lake ranged from 31.2 × 10³ to 674 × 10³ m³ day^?1 with an average of 276 × 10³ m³ day^?1. The study will be useful to delineate the possible sources of nutrients and pollutants entering the lake and for the management of lake water resources for sustainable development.