Impact of the tsunami and earthquake of 26th December 2004 on the vital coastal ecosystems of the Andaman and Nicobar Islands assessed using RESOURCESAT AWiFS data

Tsunami waves struck the Indian coast on 26th December 2004 affecting the Andaman and Nicobar group of islands. A quick assessment of the status of the vital coastal ecosystems has been made using pre- and post-tsunami Advance Wide Field Sensor (AWiFS) data of Indian satellite RESOURCESAT with an accuracy of 87–90% and the Kappa ranging from 0.8696 to 0.9053. Among the coastal ecosystems the coral reefs have suffered the maximum with the Nicobar reefs (69% eroded and 29% degraded) bearing the brunt more than the Andaman reefs (54% eroded and 22% degraded). Significant improvement to the condition of the reef damaged due to backwash has been noted. About 41% of the Sentinel reef area has undergone significant improvement. The continuance of the erosion of the southwestern Andaman reefs is due to the impact of recurring earthquakes. The impact on mangroves of both the groups of islands has been due to uprooting as well as inundation of seawater and resulting stagnation. Changes are expected in community structure of mangroves as a result of tsunami.     

Estimation of LAI and above-ground biomass in deciduous forests: Western Ghats of Karnataka, India

This study demonstrates the potentials of IRS P6 LISS-IV high-resolution multispectral sensor (IGFOV  6 m)-based estimation of biomass in the deciduous forests in the Western Ghats of Karnataka, India. Regression equations describing the relationship between IRS P6 LISS-IV data-based vegetation index (NDVI) and field measured leaf area index (ELAI) and estimated above-ground biomass (EAGB) were derived. Remote sensing (RS) data-based leaf area index (PLAI) image is generated using regression equation based on NDVI and ELAI (r² = 0.68, p ≤ 0.05). RS-based above-ground biomass (PAGB) image was generated based on regression equation developed between PLAI and EAGB (r² = 0.63, p ≤ 0.05). The mean value of estimated above-ground biomass and RS-based above-ground biomass in the study area are 280(±72.5) and 297.6(±55.2) Mg ha⁻¹, respectively. The regression models generated in the study between NDVI and LAI; LAI and biomass can also help in generating spatial biomass map using RS data alone. LISS-IV-based estimation of biophysical parameters can also be used for the validation of various coarse resolution satellite products derived from the ground-based measurements alone.     

基于MODIS数据的雪面温度遥感反演(英文)

On the basis of simplification of the Planck function in a low temperature range, this paper revises the practical split-window algorithm and presents a method for retrieving snow surface temperature （Ts） based on MODIS data in the middle-latitude region. The application of this method in Qinghai Lake region reveals that it is feasible for the retrieval of Ts. Results of correlation analysis indicate that there was strong negative relationship between Ts and altitude. By analyzing three typical areas in which land cover was relatively homogenous, this paper discusses the relationship between Ts and normalized difference snow index （NDSI） and then presents a new concept named ＂NDSI-Ts space＂.     

区域地质灾害危害程度等级划分探讨

区域性地质灾害危害程度等级尚无比较科学的划分方法。通过福建省区域地质灾害危害程度等级划分的探讨,采用单位面积地质灾害造成的人员死亡数、财产损失值作为“地质灾害模数”,对区域地质灾害危害程度等级进行划分,判别不同区域地质灾害严重程度,为区域地质灾害防治决策提供科学依据。     

贝加尔裂谷系及邻区断裂现今活动变化及成因(英文)

已有的地质和地球物理方法无法对年、月、旬等现今时间尺度上的断层活动变化进行有效预测。运用基于地震活动定量指数运算程序的地理信息技术可以解决这个问题。这种方法被应用于贝加尔裂谷系(BRS)及邻区的研究当中。研究发现,断层活动变化发生在以几年为周期的时间尺度上,这无法用区域应力场的变化进行合理解释。沿着穿越贝加尔裂谷系的剖面编制了活动断层图以及地震活动定量指数曲线。提出的这种方法可以根据地震活动定量指数对活动断层进行仔细的分类,从而为解决地震中期预报相关问题开辟了重要途径。这种方法还被用来研究断层现今活动的时空变化和形成机制。研究发现,在实时尺度上断层活动具有高频发生的特征,这种现象可能是由于脆性岩石圈板内和块体内部运动产生的慢变形波的干扰导致的。利用变形波的通过速度可以对活动断层进行分组,各组具有不同的地质和地球物理特征参数,同时还可以对变形波波前的方向以及某一区域内主要断层在实时间隔内(地质上的瞬间)的活动情况进行预测。     

汶川特大地震中山岭隧道变形破坏特征及影响因素分析

汶川大地震造成位于震中附近的都江堰-汶川公路多座隧道严重受损。本文通过现场调研、资料收集与分析,将地震区山岭隧道变形破坏的基本类型概括为洞口边坡崩塌与滑塌、洞门裂损、衬砌及围岩坍塌、衬砌开裂及错位、底板开裂及隆起、初期支护变形及开裂等。分析其影响因素,认为发震断裂的次级断层、基覆界面、洞口不稳定斜坡、高地应力环境下的软弱围岩对隧道强烈震害具有控制作用。以汶川地震给予隧道抗震的启示,建议强震区的山岭隧道应将洞口边坡防护、洞口明洞和洞门结构作为一个系统进行综合设计,在条件允许的情况下尽可能采用削竹式洞门结构;隧道穿越活动断裂带的次级断层时在其两侧一定范围内二次衬砌应采用钢筋混凝土结构;基覆界面、围岩软岩与硬岩之间的过渡地带、围岩质量突变地带等应采用改善围岩力学性质且让其渐变的措施进行处理。     

烟台市城市土地可持续利用评价

以烟台市为例,从生态环境协调性、经济可行性、社会可接受性等方面,构建了2004年城市土地可持续利用评价的指标体系,采用特尔斐等方法计算了其可持续利用度。结果表明,烟台城市土地利用目前仍处于可持续利用起步阶段。     

K-L变换与NDBI指数法提取ASTER影像城市用地信息的比较

运用K-L变换和NDBI(Normalized Difference Barren Index)指数法,对试验区--沧州市及其周边地区的ASTER遥感影像进行处理,然后分别对两种方法处理后的图像采用最小距离法监督分类,提取城市用地信息,并对分类后的图像进行对比,结果表明:NDBI指数法对城市用地信息提取的效果较好.     

纪伊半岛地区植被净初级生产力的遥感应用研究

在高光谱数据模式分解方法(PDM)的基础上,建立了一种新的植被指数(VIPD)。根据地面植被光合成实验,建立了有效光合成曲线植被净初级生产力(NPP)遥感估算模型,利用2001年各月份的MODIS影像数据,估算得到纪伊半岛地区的各类NPP。研究发现,该地区的温带常绿林NPP年均值与2001年IPCC调查报告和地面实测得到的估算值在误差范围内一致。实验证明,该光合成曲线NPP估算模型能够有效地利用高光谱数据,且能较好地应用于温带植被研究。     

空间索引与多尺度表达的一体化模型研究

在分析各种常用索引的基础上,依据各自的适用范围,提出了对点对象建立格网索引,对线、面对象建立改进四叉树索引的组合优化策略。设计的改进四叉树索引避免了传统四叉树的重复索引,提高了数据访问的效率。