scholarly journals Evaluation of Groundwater Potential and Safe Yield of Heterogeneous Unconsolidated Aquifers in Chiang Mai Basin, Northern Thailand

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 558
Author(s):  
Sutthipong Taweelarp ◽  
Morrakot Khebchareon ◽  
Schradh Saenton
Keyword(s):  
Groundwater Monitoring ◽  
Groundwater Potential ◽  
Model Parameters ◽  
Chiang Mai ◽  
Heterogeneous Aquifers ◽  
Safe Yield ◽  
Groundwater Condition ◽  
Recharge Rates ◽  
Surface Water Supply

Chiang Mai basin has an escalating population growth resulting in high demand for water consumption. Lack of surface water supply in most parts of the basin gives rise to the increasing use of groundwater which leads to a continuous decline in groundwater level in the past decades. This study is the first long-term groundwater monitoring and modeling study that aims at developing a transient, regional groundwater flow model of heterogeneous unconsolidated aquifers based on the MODFLOW program. Long-term groundwater monitoring data from 49 piezometers were used in model calibration and validation. The pilot points technique was used to account for the spatial variability of hydrogeologic parameters of heterogeneous aquifers. The simulation results and statistics showed that most sensitive and significant model parameters were spatially variable hydraulic conductivities and recharge rates. The Chiang Mai basin’s unconsolidated aquifers do not have high potential. The water table and/or potentiometric surface in the southeast and southwest areas of Chiang Mai city were continuously decreasing with no sign of recovery indicating critical groundwater condition and careful management must be considered. Safe yield calculation, based on a 2-m average drawdown threshold, suggested that unconsolidated aquifers of the Chiang Mai basin can sustain overall abstraction rates up to 51.2 Mm3/y or approximately 214% of the current extraction rates.

scholarly journals Agglomeration economies, congestion diseconomies, and fertility dynamics in a two-region economy

2021 ◽  
Author(s):  
Madoka Muroishi ◽  
Akira Yakita
Keyword(s):  
Population Size ◽  
Stability Condition ◽  
Fertility Rate ◽  
Model Parameters ◽  
Initial Population ◽  
Interregional Migration ◽  
Stable Path ◽  
Regional Population ◽  
Initial Population Size

AbstractUsing a small, open, two-region economy model populated by two-period-lived overlapping generations, we analyze long-term agglomeration economy and congestion diseconomy effects of young worker concentration on migration and the overall fertility rate. When the migration-stability condition is satisfied, the distribution of young workers between regions is obtainable in each period for a predetermined population size. Results show that migration stability does not guarantee dynamic stability of the economy. The stationary population size stability depends on the model parameters and the initial population size. On a stable trajectory converging to the stationary equilibrium, the overall fertility rate might change non-monotonically with the population size of the economy because of interregional migration. In each period, interregional migration mitigates regional population changes caused by fertility differences on the stable path. Results show that the inter-regional migration-stability condition does not guarantee stability of the population dynamics of the economy.

scholarly journals Study on creep performance of launch canister under long-term storage

2019 ◽  
Vol 43 (2) ◽  
pp. 199-208 ◽  
Author(s):  
Cun-Gui Yu ◽  
Tong-Sheng Sun ◽  
Guang-Yuan Xiao
Keyword(s):  
Residual Deformation ◽  
Bottom Layer ◽  
Tensile Creep ◽  
Creep Model ◽  
Model Parameters ◽  
Creep Tests ◽  
Software Environment ◽  
Long Term Storage ◽  
Term Storage

In this paper, the creep performance of a multi-barrel rocket launch canister under long-term stacking storage is studied. Based on the Bailey–Norton model, a creep model for the frame material of a launch canister was established. Constant stress tensile creep tests under different stress levels at room temperature were carried out on the frame materials of the launch canister and the creep model parameters were obtained by test data fitting. The three-dimensional finite element model of the launch canister was established in the ABAQUS software environment and the creep deformation of the launch canister after long-term stacking storage was studied. The results indicated that the bottom layer of the launch canister frame presented an extended residual deformation when the stacking storage solution with the original support pad was used. Therefore, a position adjustment program of the support pad was put forward. The residual deformation of the launch canister frame after long-term storage could be significantly reduced, thus the performance requirements for the launch canister are guaranteed.

Warming is Driving Decreases in Snow Fractions While Runoff Efficiency Remains Mostly Unchanged in Snow-Covered Areas of the Western United States

2018 ◽  
Vol 19 (5) ◽  
pp. 803-814 ◽  
Author(s):  
Gregory J. McCabe ◽  
David M. Wolock ◽  
Melissa Valentin
Keyword(s):  
United States ◽  
Time Series ◽  
Winter Precipitation ◽  
Western United States ◽  
Balance Model ◽  
Winter Temperatures ◽  
Long Term Trends ◽  
Monthly Water Balance ◽  
Surface Water Supply

Abstract Winter snowfall and accumulation is an important component of the surface water supply in the western United States. In these areas, increasing winter temperatures T associated with global warming can influence the amount of winter precipitation P that falls as snow S. In this study we examine long-term trends in the fraction of winter P that falls as S (Sfrac) for 175 hydrologic units (HUs) in snow-covered areas of the western United States for the period 1951–2014. Because S is a substantial contributor to runoff R across most of the western United States, we also examine long-term trends in water-year runoff efficiency [computed as water-year R/water-year P (Reff)] for the same 175 HUs. In that most S records are short in length, we use model-simulated S and R from a monthly water balance model. Results for Sfrac indicate long-term negative trends for most of the 175 HUs, with negative trends for 139 (~79%) of the HUs being statistically significant at a 95% confidence level (p = 0.05). Additionally, results indicate that the long-term negative trends in Sfrac have been largely driven by increases in T. In contrast, time series of Reff for the 175 HUs indicate a mix of positive and negative long-term trends, with few trends being statistically significant (at p = 0.05). Although there has been a notable shift in the timing of R to earlier in the year for most HUs, there have not been substantial decreases in water-year R for the 175 HUs.

Methods for Minimization and Management of Variability in Long Term Groundwater Monitoring Results

2015 ◽  
Author(s):  
Thomas E. McHugh ◽  
Poonam R. Kulkarni ◽  
Charles J. Newell ◽  
Sanford L. Britt
Keyword(s):  
Groundwater Monitoring

scholarly journals Streamflow recession patterns can help unravel the role of climate and humans in landscape co-evolution

2016 ◽  
Vol 20 (4) ◽  
pp. 1413-1432 ◽  
Author(s):  
Patrick W. Bogaart ◽  
Ype van der Velde ◽  
Steve W. Lyon ◽  
Stefan C. Dekker
Keyword(s):  
Land Cover ◽  
Base Flow ◽  
Natural Soil ◽  
Model Parameters ◽  
Linear Behaviour ◽  
Forested Areas ◽  
Future Landscape ◽  
Do So

Abstract. Traditionally, long-term predictions of river discharges and their extremes include constant relationships between landscape properties and model parameters. However, due to the co-evolution of many landscape properties more sophisticated methods are necessary to quantify future landscape–hydrological model relationships. As a first step towards such an approach we use the Brutsaert and Nieber (1977) analysis method to characterize streamflow recession behaviour of  ≈  200 Swedish catchments within the context of global change and landscape co-evolution. Results suggest that the Brutsaert–Nieber parameters are strongly linked to the climate, soil, land use, and their interdependencies. Many catchments show a trend towards more non-linear behaviour, meaning not only faster initial recession but also slower recession towards base flow. This trend has been found to be independent from climate change. Instead, we suggest that land cover change, both natural (restoration of natural soil profiles in forested areas) and anthropogenic (reforestation and optimized water management), is probably responsible. Both change types are characterised by system adaptation and change, towards more optimal ecohydrological conditions, suggesting landscape co-evolution is at play. Given the observed magnitudes of recession changes during the past 50 years, predictions of future river discharge critically need to include the effects of landscape co-evolution. The interconnections between the controls of land cover and climate on river recession behaviour, as we have quantified in this paper, provide first-order handles to do so.

scholarly journals Decline in Transparency of Lake Hongze from Long-Term MODIS Observations: Possible Causes and Potential Significance

2019 ◽  
Vol 11 (2) ◽  
pp. 177 ◽  
Author(s):  
Na Li ◽  
Kun Shi ◽  
Yunlin Zhang ◽  
Zhijun Gong ◽  
Kai Peng ◽  
...  
Keyword(s):  
Water Quality ◽  
Aquatic Vegetation ◽  
Water Quality Monitoring ◽  
Validation Dataset ◽  
Model Parameters ◽  
Potential Significance ◽  
Important Indicator ◽  
Quality Issue ◽  
Mean Square Errors

Transparency is an important indicator of water quality and the underwater light environment and is widely measured in water quality monitoring. Decreasing transparency occurs throughout the world and has become the primary water quality issue for many freshwater and coastal marine ecosystems due to eutrophication and other human activities. Lake Hongze is the fourth largest freshwater lake in China, providing water for surrounding cities and farms but experiencing significant water quality changes. However, there are very few studies about Lake Hongze’s transparency due to the lack of long-term monitoring data for the lake. To understand long-term trends, possible causes and potential significance of the transparency in Lake Hongze, an empirical model for estimating transparency (using Secchi disk depth: SDD) based on the moderate resolution image spectroradiometer (MODIS) 645-nm data was validated using an in situ dataset. Model mean absolute percentage and root mean square errors for the validation dataset were 27.7% and RMSE = 0.082 m, respectively, which indicates that the model performs well for SDD estimation in Lake Hongze without any adjustment of model parameters. Subsequently, 1785 cloud-free images were selected for use by the validated model to estimate SDDs of Lake Hongze in 2003–2017. The long-term change of SDD of Lake Hongze showed a decreasing trend from 2007 to 2017, with an average of 0.49 m, ranging from 0.57 m in 2007 to 0.42 m in 2016 (a decrease of 26.3%), which indicates that Lake Hongze experienced increased turbidity in the past 11 years. The loss of aquatic vegetation in the northern bays may be mainly affected by decreases of SDD. Increasing total suspended matter (TSM) concentration resulting from sand mining activities may be responsible for the decreasing trend of SDD.

Nitrogen mineralisation in sugarcane soils in Queensland, Australia: I. evaluation of soil tests for predicting nitrogen mineralisation

Soil Research ◽  
2019 ◽  
Vol 57 (7) ◽  
pp. 738 ◽  
Author(s):  
D. E. Allen ◽  
P. M. Bloesch ◽  
T. G. Orton ◽  
B. L. Schroeder ◽  
D. M. Skocaj ◽  
...  
Keyword(s):  
Soil Properties ◽  
Mixed Effects ◽  
Mixed Effects Model ◽  
Co2 Production ◽  
Organic N ◽  
Model Parameters ◽  
Nitrogen Mineralisation ◽  
Short Term ◽  
Available N

We explored soil properties as indices of mineralisable nitrogen (N) in sugarcane soils and whether we could increase the accuracy of predicting N mineralisation during laboratory incubations. Utilising historical data in combination with samples collected during 2016, we: (i) measured mineralised N over the course of short-term (14 days) and long-term (301 days) laboratory incubations; (ii) compared models representing mineralisation; then (iii) related model parameters to measured soil properties. We found measures representing the labile organic N pool (Hydrolysable NaOH organic N; amino sugar Illinois soil N test) best related to short-term mineralised N (R2 of 0.50–0.57, P < 0.001), while measures of CO2 production (3, 7, 10 and 14 days) best related to longer-term mineralised N (R2 of 0.75–0.84, P < 0.001). Indices were brought together to model the active and slow pools of a two-pool mineralisation model in the statistical framework of a mixed-effects model. Of the models that relied on measurement of one soil property, cumulative CO2 production (7 days) performed the best when considering all soil types; in a cross-validation test, this model gave an external R2 of 0.77 for prediction of the 301-day mineralised N. Since the mixed-effects model accounts for the various sources of uncertainty, we suggest this approach as a framework for prediction of in-field available N, with further measurement of long-term mineralised N in other soils to strengthen predictive certainty of these soil indices.

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