Modelling Land Use/Land Cover Change of River Rwizi Catchment, South-Western Uganda Using GIS and Markov Chain Model

Analysis of catchment Land use/Land cover (LULC) change is a vital tool in ensuring sustainable catchment management. The study analyzed land use/land cover changes in the Rwizi catchment, south western Uganda from 1989-2019 and projected the trend by 2040. Landsat images, field observations, key informant interviews and focus group discussions were used to collect data. Changes in cropland, forestland, built up area, grazing land, wetland and open water bodies were analyzed in ArcGIS version 10.2.2 and ERDAS IMAGINE 14 software and a Markov chain model. All the LULC classes increased in area except grazing land. Forest land and builtup area between 2009-2019 increased by 370.03% and 229.53% respectively. Projections revealed an increase in forest land and builtup area by 2030 and only built up area by 2040. LULCC in the catchment results from population pressure, reduced soil fertility and high value of agricultural products.

Model based decision support system for land use changes and socio-economic assessments

Hydrological models are often linked with other models in cognate sciences to understand the interactions among climate, earth, water, ecosystem, and human society. This paper presents the development and implementation of a decision support system（DSS） that links the outputs of hydrological models with real-time decision making on social-economic assessments and land use management. Discharge and glacier geometry changes were simulated with hydrological model, water availability in semiarid environments. Irrigation and ecological water were simulated by a new commercial software MIKE HYDRO. Groundwater was simulated by MODFLOW. All the outputs of theses hydrological models were taken as inputs into the DSS in three types of links： regression equations, stationary data inputs, or dynamic data inputs as the models running parallel in the simulation periods. The DSS integrates the hydrological data, geographic data, social and economic statistical data, and establishes the relationships with equations, conditional statements and fuzzy logics. The programming is realized in C＋＋. The DSS has four remarkable features：（1） editable land use maps to assist decision-making;（2） conjunctive use of surface and groundwater resources;（3） interactions among water, earth, ecosystem, and humans; and（4） links with hydrological models. The overall goal of the DSS is to combine the outputs of scientific models, knowledge of experts, and perspectives of stakeholders, into a computer-based system, which allows sustainability impact assessment within regional planning; and to understand ecosystem services and integrate them into land and water management.

Impacts of Land Process on the Onset and Evolution of Asian Summer Monsoon in the NCEP Climate Forecast System

Impacts of land models and initial land conditions （ICs） on the Asian summer monsoon, especially its onset, were investigated using the NCEP Climate Forecast System （CFS）. Two land models, the Oregon State University （OSU） land model and the NCEP, OSU, Air Force, and Hydrologic Research Laboratory （Noah） land model, were used to get parallel experiments NCEP/Department of Energy （DOE） Global Reanalysis 2 System （GLDAS）. The experiments also used land ICs from the （GR2） and the Global Land Data Assimilation Previous studies have demonstrated that, a systematic weak bias appears in the modeled monsoon, and this bias may be related to a cold bias over the Asian land mass. Results of the current study show that replacement of the OSU land model by the Noah land model improved the model＇s cold bias and produced improved monsoon precipitation and circulation patterns. The CFS predicted monsoon with greater proficiency in E1 Nifio years, compared to La Nifia years model in monsoon predictions for individual years. and the Noah model performed better than the OSU These improvements occurred not only in relation to monsoon onset in late spring but also to monsoon intensity in summer. Our analysis of the monsoon features over the India peninsula, the Indo-China peninsula, and the South Chinese Sea indicates different degrees of improvement. Furthermore, a change in the land models led to more remarkable improvement in monsoon prediction than did a change from the GR2 land ICs to the GLDAS land ICs.

Study of prediction for groundwater contamination in wastewater land treatment system

This paper uses a prediction model of groundwater pollution based on the experiments in the laboratory and in field .The model, which was tested and calibrated by the field observated data ,satisfactorily simulated the field conditions in land treatment system of wastewater . Particularly , the model can provide the reliable pollution prediction of heavy metals , organisms and nitrogen . The model was used to predict the groundwater pollution caused by the land treatment system in the region of North China . The calibration of the model showed that correlation coefficients between the tested and predictive data of Cr6+. As3+, organism and NH4+ could reach 0.990, which proved that the model possessed the realistic instructive significance for design and use of wastewater land treatment systems .

Techno-economic analysis of municipal wastewater land treatment systems in China

This paper analyses the capital costs, power consumption and operation costs of municipal wastewater land treatment systems, including rapid infiltration, slow-rate infiltration, overflow and constructed wetland, by means of series engineering design. The results show that land treatment can save 50-70% of capital costs, 80-90% of power and 75-85% of operation costs when compared with secondary treatment.

Design and Dynamics Analysis of Anti-skid Braking System for Aircraft with Four-wheel Bogie Landing Gears

In asymmetric conditions,the movement and loads of left/right wheels or front/back wheels of the aircraft with multi-wheel or four-wheel bogie landing gears are inconsistent.There are few open literatures related to anti-skid braking system for multi-wheels due to technology blockade.In China,the research on multi-channel control and non-equilibrium regulation has just started,and the design of multi-channel control system for anti-skid braking,the simulation of asymmetry taxiing under braking are not studied.In this paper,a dynamics model of ground movement for aircraft with four-wheel bogie landing gears is established for braking simulation, considering the six-degree-of-freedom aircraft body and the movement of bogies and wheels.A multi-channel anti-skid braking system is designed for the wheels of the main landing gears with four-wheel bogies.The eight wheels on left and right landing gears are divided into four groups,and each group is controlled via one channel.The cross protection and self-locked protection modules are added between different channels.A multi-channel anti-skid braking system with slip-ratio control or with slip-velocity control is established separately.Based on the aircraft dynamics model,aircraft braking to stop with anti-skid control on dry runway and on wet runway are simulated.The simulation results demonstrate that in asymmetric conditions,added with cross protection and self-locked protection modules,the slip-ratio-controlled braking system can automatically regulate brake torque to avoid deep slipping and correct aircraft course.The proposed research has reference value for improving brake control effect on wet runway.

Identification of landing sites for rescue helicopters in mountains with use of Geographic Information Systems

Helicopters are often used in mountain rescue both for rescuers moving in the area of accidents and for evacuating victims, but in steep or forested terrain finding a landing place can be problematic. The main aim of this research is to use Digital Elevation Model(DEM) and cartographic database analysis to select locations that can be used as landing site for the rescue helicopters. Methods were based on GIS analysis;both raster and vector data were used for identifying touchdown points for rescue helicopters. Based on DEM data, locations with a low slope gradient were identified;topographic vector data were used for identifying unforested sites. Then buffer zones for buildings and power lines were excluded, and it was checked whether the areas had any topographic features that prevented helicopter landings. The findings were verified on an orthophotomap. In result, GIS analyses have selected 1232 polygons that fulfilled initial criteria. Their verification on orthophotomap has shown that only 55% of them could be potentially used as landing site. Landing sites can be found mainly on side ridges of mountain ranges and in valley beds, when those on ridges are most important in this research. The greatest difficulties and methodological challenges are posed by: identification of sites having a shape which prevents landing, the obsolescence of data due to environment dynamics, the presence of features that are not shown on maps but prevent helicopter landings. A map of landing sites is a very useful tool to conduct rescue operations, but each use of a given landing site requires both in-field and numerical verification. The analysis demonstrated that GIS toolsare useful in pre-planning of rescue missions, and also showed that such data must be kept up-to-date and in-field verification is needed continuously, the more so as it plays an important role in ensuring the safety of rescuers and victims.

Land Response to Atmosphere at Different Resolutions in the Common Land Model over East Asia

Towards a better understanding of hydrological interactions between the land surface and atmosphere, land surface mod- els are routinely used to simulate hydro-meteorological fluxes. However, there is a lack of observations available for model forcing, to estimate the hydro-meteorological fluxes in East Asia. In this study, Common Land Model （CLM） was used in offline-mode during the summer monsoon period of 2006 in East Asia, with different forcings from Asiaflux, Korea Land Data Assimilation System （KLDAS）, and Global Land Data Assimilation System （GLDAS）, at point and regional scales, separately. The CLM results were compared with observations from Asiaflux sites. The estimated net radiation showed good agreement, with r = 0.99 for the point scale and 0.85 for the regional scale. The estimated sensible and latent heat fluxes using Asiaflux and KLDAS data indicated reasonable agreement, with r = 0.70. The estimated soil moisture and soil temperature showed similar patterns to observations, although the estimated water fluxes using KLDAS showed larger discrepancies than those of Asiaflux because of scale mismatch. The spatial distribution of hydro-meteorological fluxes according to KLDAS for East Asia were compared to the CLM results with GLDAS, and the GLDAS provided online. The spatial distributions of CLM with KLDAS were analogous to CLM with GLDAS, and the standalone GLDAS data. The results indicate that KLDAS is a good potential source of high spatial resolution forcing data. Therefore, the KLDAS is a promising alternative product, capable of compensating for the lack of observations and low resolution grid data for East Asia.

The Performance of Atmospheric Component Model R42L9 of GOALS/LASG

This paper examines the performance of an atmospheric general circulation model (AGCM) developed at the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics (LASG/IAP). It is a spectral model truncated at R42(2.8125°long×1.66°lat) resolution and with nine vertical levels, and referred to as R42L9/LASG hereafter. It is also the new version of atmospheric component model R15L9 of the global ocean-atmosphere-land system (GOALS/LASG). A 40-year simulation in which the model is forced with the climatological monthly mean sea surface temperature is compared with the 40-year (1958-97) U.S. National Center for Environmental Prediction (NGEP) global reanalysis and the 22-year (1979-2000) Xie-Arkin monthly precipitation climatology. The mean DJF and JJA geographical distributions of precipitation, sea level pressure, 500-hPa geopotential height, 850-hPa and 200-hPa zonal wind, and other fields averaged for the last 30-year integration of the R42L9 model are analyzed. Results show that the model reproduces well the observed basic patterns, particularly precipitation over the East Asian region. Comparing the new model with R15L9/LASG, the old version with coarse resolution (nearly 7.5°long×4.5°lat), shows an obvious improvement in the simulation of regional climate, especially precipitation. The weaknesses in simulation and future improvements of the model are also discussed.

A grey multi-objective programming approach for sustainable land-use in the Miyun Reservoir Basin,China

Miyun Reservoir is the most important water source to Beijing City. Land-use of the basin plays a great role in the protection of water resources. Hence a sustainable land-use planning is required to optimize land-use structure and protect water resources in the basin. Based on the complete land-use system analysis in Miyun, a grey multi-objective programming to basin land-use(GMOPBLU) model was developed and applied to land-use planning. Two alternatives were produced and analyzed by means of interactive adjustment and scenario analysis. The results showed the GMOPBLU model is a valuable approach for basin land-use planning.

Safety analysis of wheel brake system based on STAMP/STPA and Monte Carlo simulation

The wheel brake system safety is a complex problem which refers to its technical state, operating environment, human factors, etc., in aircraft landing taxiing process. Usually, professors consider system safety with traditional probability techniques based on the linear chain of events. However, it could not comprehensively analyze system safety problems, especially in operating environment, interaction of subsystems, and human factors. Thus,we consider system safety as a control problem based on the system-theoretic accident model, the processes(STAMP) model and the system theoretic process analysis(STPA) technique to compensate the deficiency of traditional techniques. Meanwhile,system safety simulation is considered as system control simulation, and Monte Carlo methods are used which consider the range of uncertain parameters and operation deviation to quantitatively study system safety influence factors in control simulation. Firstly,we construct the STAMP model and STPA feedback control loop of the wheel brake system based on the system functional requirement. Then four unsafe control actions are identified, and causes of them are analyzed. Finally, we construct the Monte Carlo simulation model to analyze different scenarios under disturbance. The results provide a basis for choosing corresponding process model variables in constructing the context table and show that appropriate brake strategies could prevent hazards in aircraft landing taxiing.

耦合GCAM和GlobeLand30的CLUMondo模型及其适用性评估

本文在CLUMondo模型中了耦合全球变化评估模型(globalchangeassessmentmodel,GCAM)和GlobeLand30数据.其中:GCAM为土地变化预测提供科学的土地系统服务数值;GlobeLand30用于制备可赋予多重土地系统服务供给能力的土地系统数据.为验证模型的有效性,本文选择了GCAM中的“青藏高原内部区”进行验证.结果表明:1)GCAM可以有效解决CLUMondo模型在土地变化模拟时设置土地系统服务的困境;2)对GlobeLand30数据升尺度建立土地系统,为CLUMondo模型量化多重土地系统服务供给能力提供了一种简单高效的方法;3)耦合GCAM和GlobeLand30数据后的CLUMondo模型在“GCAM青藏高原内部区”具有良好的适用性.

船载投料系统饲料颗粒流落点预测

【目的】为解决网箱养殖中使用船载投料系统的饲料颗粒流落点控制问题,提出一种用于实时分割饲料颗粒流轨迹并精确预测其落点的方法(MLBP)。【方法】考虑到输料管管内参数及饲料颗粒流出口参数获取难度较大,本研究采用高速相机获取饲料颗粒流轨迹图像,并利用提出的混合网络模型分割饲料颗粒流轨迹,以获取轨迹关键信息;为准确预测饲料颗粒流落点,利用BP神经网络的优势,将轨迹信息及投料口高度作为其输入,实现饲料颗粒流落点的预测。【结果】与相关研究方法对比,结合混合网络模型与BP神经网络的MLBP方法的系统单次运行时间降低95%,同时落点预测准确度达到96%,落点的平均误差范围与平均误差百分比也分别降低32.0%和30.5%。【结论】本研究提出的MLBP方法预测精度及实时性均能满足网箱投饵作业需求,可为相关研究提供参考。

资源型城市转型背景下土地利用结构的模拟与预测

[目的]资源型城市作为国家资源能源安全的重要保障城市,其转型发展方式更应向高质量方向推进。研究资源型城市转型背景下土地利用结构的变化并进行预测模拟,为新时期资源型城市国土空间优化提供新思路。[方法]基于资源型城市转型发展的概念及内涵,分析经济、社会、人口、科技、资源环境5个维度的系统性影响,并与空间布局相关联,构建系统动力学模型,以安徽省铜陵市2005—2020年的历史数据为参照,将2021—2035年的数据设置仿真情境,进行土地利用结构的多情境趋势性预测分析。[结果](1)铜陵市土地利用和经济发展现状奠定了发展的基础,可以此为依据进行转型条件设置和土地利用结构变化的合理预测。(2)资源型城市转型发展作为一个系统性概念,形成“系统—指标—要素”的层级框架,不仅相互关联,密不可分,还传导作用于不同的地类,影响土地利用系统。(3)铜陵市2021—2035年地类的情境趋势发展差异较为相似,即耕地、林地、水域、草地和未利用地的减少幅度自经济发展、社会进步、综合发展而递减,在资源保护情境下面积均有小幅度提升。建设用地则相反,增加幅度随经济发展、社会进步、综合发展而递减,在资环保护情境下扩张速度得到一定程度的控制。[结论]资源型城市的新时期转型,不仅要将内在要素融合成系统性概念,还要提升土地利用系统的关注度,重视结构合理性和发展协调性。

农地确权对农民市民化的影响研究

农地确权为农民土地提供法律保护,理论上有助于推动农民市民化。本文利用2013—2019年间四期中国农村家庭追踪调查数据和渐进DID模型,实证考察农地确权对农民市民化的影响。研究发现,农地确权通过促进非农就业改善农民市民化行为,且这种效应在非粮食主产区和人口净流入省份更为明显;农地确权也提高了农民市民化意愿,该效应在所有成员为农业户籍的家庭中更为突出。因此,未来既要因地制宜,消除进城农民失去土地的顾虑,也要因户施策,开通农民城市落户的绿色通道。

基于能量系统语言的土地流转能量流动过程模拟——以河北太行山区东高昌村为例

利用河北太行山区东高昌村2016−2019年土地流转数据,运用ESL(energy system language)模型对河北太行山区土地流转前后过程进行模拟评价,基于土地利用情景和劳动力投入视角进一步模拟了土地流转后系统能量变动情况.结果表明:1)土地流转后农作物生物量、资本及生态环境相比土地流转前均有显著提升.10年后农作物生物量、资本和林地生物量分别达到土地流转前的12.97、2.10、36.54倍;50年后农作物生物量、资本和林地生物量分别达到土地流转前的15.34、4.23、39.22倍;100年后农作物生物量、资本和林地生物量分别达到土地流转前的26.79、7.39、66.60倍.2)改变种植结构的流转效果一般,但调整劳动力投入结构使土地流转后的南瓜生物量和资本呈现倒“U”形变化趋势,南瓜生物量在24年达到峰值,资本在48年达到峰值.投入当地劳动力使农作物生物量提高46.5%,资本提高212%,效果最为显著.

弱引力双小行星系统的低能着陆轨道设计

针对在弱引力双小行星系统环境下,探测器无动力或仅具有微弱机动能力时的表面着陆问题,提出基于不稳定流形和庞加莱截面法的低能着陆轨道设计方法.通过搜索共线平动点附近的周期轨道,计算单值矩阵的特征值及特征向量,求解周期轨道的不稳定流形,大幅减少了着陆过程中的燃料消耗.对于有微弱机动能力的着陆器,提出不稳定流形和下降轨道集拼接的轨道设计方法,获得满足末端约束的低能着陆轨道.通过数值仿真验证:与遗传算法计算双脉冲着陆轨迹方法相比,本文所提方法可以灵活地添加末端约束以及设计目标着陆点,且不需要设计惩罚函数以及进行迭代运算,计算效率高.与完全自然着陆的低能量着陆轨迹相比,该方法能够有效地扩大着陆候选区域.

Developing land use scenario dynamics model by the integration of system dynamics model and cellular automata model

Modeling land use scenario changes and its potential impacts on the structure and function of the ecosystem in the typical regions are helpful to understanding the interactive mechanism between land use system and ecological system. A Land Use Scenario Dynamics (LUSD) model by the integration of System Dynamics (SD) model and Cellular Automata (CA) model is developed with land use scenario changes in northern China in the next 20 years simulated in this paper. The basic idea of LUSD model is to simulate the land use scenario de-mands by using SD model at first, then allocate the land use scenario patterns at the local scale with the considerations of land use suitability, inheritance ability and neighborhood effect by using CA model to satisfy the balance between land use scenario demands and supply. The application of LUSD model in northern China suggests that the model has the ability to reflect the complex behavior of land use system at different scales to some extent and is a useful tool for assessing the potential impacts of land use system on ecological system. In addition, the simulated results also indicate that obvious land use changes will take place in the farming-pastoral zone of northern China in the next 20 years with cultivated land and urban land being the most active land use types.

耕地“三位一体”保护视角下中国省域休耕规模与空间布局

实施土地休耕是落实“藏粮于地”战略的关键,目前宏观尺度的全国休耕空间布局尚未确定,该研究探究了粮食安全约束下的全国范围内最大休耕规模以及中国省域休耕空间优化布局。以耕地数量、质量和生态“三位一体”保护为研究视角,该研究通过系统动力学、灰色预测模型等方法构建最大休耕规模预测模型,并结合“压力-状态-响应”模型构建休耕迫切度评价体系,依据评价结果分配各省休耕规模,从而得到中国省域休耕空间布局。结果表明:1)预计在90%、95%、100%的粮食自给率下,到2030年中国最大休耕规模分别为3237.310万、2678.970万和2120.640万hm^(2);2)省域之间的休耕迫切度水平存在差异,上海、内蒙古等地休耕迫切度较高,四川、广西等地休耕迫切度较低;3)在耕地三位一体保护的约束条件下,地区之间休耕规模差异较大,内蒙古、甘肃等地休耕规模较大,北京、上海等地休耕规模较小。该研究将数量、质量和生态多元目标融合进休耕空间分区研究,能够为未来休耕制度的全面建立以及精准落地提供思路与方法参考。

地铁站点区域交通与土地利用协调性分析

【目的】随着城市化进程不断加快,城市交通拥挤、环境污染、用地紧张等问题日趋严重。城市交通拥挤的主要原因之一在于交通供给与土地利用之间的不协调。地铁站点周边交通与土地利用的协调性分析有利于促进城市交通建设的可持续发展。【方法】本文基于节点-场所模型(Node-Place Model,N-P Model),考虑使用节点价值与场所价值的比值对传统模型进行优化,同时通过运用地理信息系统(geographic information system,GIS),选取站点场所功能和节点功能多个评价指标,并结合熵权-TOPSIS(technique for order preference by similarity to ideal solution)评价法构建站点协调度评价体系,最后获得站点排名情况、轨道交通站点周边交通与土地利用的协调水平。【结果】本文对长沙市轨道交通二号线部分站点进行协调性分析。其结果表明,优化后的模型与传统的模型存在差异,且大部分站点地区协同程度较高,但协调性存在差异。本文对协调性差的站点提出了相应的优化策略。【结论】轨道交通站点区域交通与土地利用的协调性分析能为城市轨道交通发展提供理论参考,有利于城市交通可持续发展。