Akihiko Kondoh

Changes in hydrological cycle due to urbanization in the suburb of Tokyo Metropolitan area, Japan

Abstract The suburbs of Tokyo Metropolitan area has been experiencing heavy land use/cover changes followed by modernization of Japan. The stages of land surface alteration can be precisely monitored by satellite remote sensing data and available maps. Image processing system and Geographic Information System are used to draw land use/cover, and map the changes on the surface. After delineating the urbanization process, the changes in hydrological cycle should be assessed to understand what has been changed due to mans impact on the surface. In this paper, changes in areal evapotranspiration due to urbanization and the response of groundwater flow system for changing recharge are evaluated. As a result, decrease in evapotranspiration is assessed quantitatively, and it is clarified that the effect of decreasing recharge is large in local ground water system in upper stream.

Using GIS-Based Weighted Linear Combination Analysis and Remote Sensing Techniques to Select Optimum Solid Waste Disposal Sites within Mafraq City, Jordan

Landfill siting was determined within Mafraq City, Jordan, through the integration of geographic information system (GIS), weighted linear combination (WLC) analysis, and remote sensing techniques. Several parameters were collected from various sources in vector and raster GIS formats, and then, used within the GIS-based WLC analysis to select optimum solid waste disposal sites. Namely, urban areas, agricultural lands, access roads, surface aquifers, groundwater table, fault system, water wells, streams, and land slope were considered in this research. Also, the trend of urban expansion within the study area was monitored using the Landsat data of 1989, 1999, and 2009 to support the selection process of disposal sites. It is found that about 84% of the study area was within “most suitable” to “moderately suitable” classes for landfill sites, while the rest of the study area was within “poorly suitable” and “unsuitable” classes. Based on the analysis of Landsat satellite data the urban area was expanded of more than 240% during the last three decades, mainly toward south, and southwest, except the villages near the existing disposal site, where the trend was toward east and northeast. Finally, three sites were suggested as alternatives to the existing disposal site taking into the consideration the environmental, biophysical, and economical variables applied in the GIS-based WLC analysis.

The forest vegetation and its differentiation under disturbance in a temperate mountain, China

Composition and structure of the main forest types, as well as the species changes under disturbance, were described as the representation of the forest vegetation in the north slope of Changbai mountain, northeast China. There were 3 forest zones from 600 m to 2,000 m asl, (1) broad-leaved-conifer mixed forest zone, 600–1,100 m asl, dominated byPinus koraiensis, Tilia amurensis, Acer mono, Ulmus japonica, (2) coniferous forest zone, 1,100–1,700 m asl, dominated byPicea jezoensis var.komarovii, P. koraiensis, Abies nephrolepis, and (3)Betula ermanii forest zone, 1,700–2,000 m asl, dominated byBetula ermanii, except for the east slope which was occupied byLarix olgensis. The evergreen component increased with elevation up to the upper limit of the coniferous forest zone (1,700 m), but disappeared in theB. ermanii zone. Species richness was significantly related to elevation. Towards higher elevation, the lapse rate of species-number was 1.6 species per 100 m, and it was only one species near the timberline. Species richness was reduced sharply under intensive disturbance, such as clear cutting, windfalletc. The species diversity was very low in the early stage of succession, and high in the later.

Monitoring surface moisture and vegetation status by NOAA and GMS over North China Plain

Abstract North China Plain(NCP) is the main granary in China, however, NCP is confronted with water shortage problem that may lead to the fall of the crop production. Thus monitoring NCP from space is very important to know how hydrologic environment affects the crop production. NCP has been monitored by using NOAA/AVHRR for vegetation conditions. As a result, it is clarified that surface hydrological conditions clearly affect the crop production rate revealed by NDVI. Then the surface wetness is estimated by NOAA/AVHRR and GMS/S-VISSR. The slope parameter in the scattergram between vegetation index and surface temperature is examined from NOAA/AVHRR data. The difference in brightness temperatures between 8:00AM and 10:00AM(LT) is also investigated from GMS data. Both of these are considered to be the index of surface moisture condition. The distributions of surface wetness obtained from both methods agree mutually with each other. The results will be used for water management such as proper irrigation practice.

Effect of Urban Aquifer Exploitation on Subsurface Temperature and Water Quality

Groundwater pumping induces changes in the hydrodynamics of aquifer systems. Rapid urbanization and pumping-induced changes in local groundwater flow can change the natural heat and chemical balances of an aquifer. In the Nagaoka Plain, Japan, groundwater is being extracted at 145 × 10(6) m3 /year from a highly permeable aquifer consisting of coarse-grained sediments of Late Pleistocene to Holocene age. We used land-cover and groundwater analyses to investigate the processes that change subsurface temperature and water quality induced by urbanization and intensive groundwater extraction. Comparison of temperature and water quality measurements in 2009 with measurements made between 1977 and 2000 revealed an increase in subsurface temperature (at 18 m depth) of 0.050 °C/year in the main urban area of the Nagaoka Plain, which is equivalent to the rate of increase of mean air temperature during that period. The effects of surface warming are apparent as a warm zone under the urban area. An area with low saturation index of calcite (-3.0 to -2.0) was centered around urban areas in 2009, whereas in 2000 the index there was higher (-1.5 to -0.5). The decrease in this index in the center of Nagaoka City over the last decade is consistent with continuous dissolution of carbonates induced there by changes in recharge water sources due to groundwater pumping. These findings suggest that urbanization, intensive groundwater extraction, and recharge with chemically modified surface water are responsible for changes in thermal and chemical properties under the urban area of the Nagaoka Plain.

Relationship among the surface albedo, spectral reflectance of canopy, and evaporative fraction at grassland and paddy field

Abstract For the purpose of estimating land surface fluxes over a large area, use of remote sensing techniques is and will be essential. Particularly, “ in situ ” collection of ground truth data has been a very important task for the development of satellite oriented “ algorithms ”. In this study, we observed “a patch scale” visible and near infrared spectral reflectance, which is obtainable from satellites, and land surface fluxes during and post-growing season at grassland and paddy field: Seasonal trends at grassland and at paddy field were quite different, because of the differences in water as well as growing environment. A good direct correlation was found between vegetation index (NDVI) and surface resistance during the growing season at grassland. A similar result was confirmed between NDVI and surface resistance at paddy field.

Study of changes in life zone distribution in north-east China by climate–vegetation classification

Life zones and their changes in distribution in north-east China were studied based on climate–vegetation relationships. The warmth index (WI) and aridity index (the ratio of evaporation [evaporation rate, ER] to precipitation) were used to represent the site condition. The typical site condition of each vegetation type was determined as the classification criterion. The boundaries of the four potential vegetation zones were estimated based on the combinations of WI and ER in relation to vegetation (i.e. cold-temperate conifer forest zone, temperate broad-leaved conifer mixed forest zone, warm-temperate deciduous forest zone, and temperate steppe zone). The distribution changes in vegetation zone caused by human activities were estimated by comparing the potential vegetation with the actual one. The percentage cover of forest has shrunk from about 70% to the present 27%. About 23% of the study area was replaced by agricultural vegetation and industrial use. Nearly half of the region could have been covered by broad-leaved conifer mixed forest which was shrunk to a small area, less than 5% of the region. The broad-leaved deciduous forest zone in the southern part could have occupied about 7% of the area, and had almost no virgin stand.

Remote sensing applications with NH hyperspectral portable video camera

Recent advances in image sensor and information technologies have enabled the development of small hyperspectral imaging systems. EBA JAPAN (Tokyo, Japan) has developed a novel grating-based, portable hyperspectral imaging camera NH-1 and NH-7 that can acquire a 2D spatial image (640 x 480 and 1280 x 1024 pixels, respectively) with a single exposure using an internal self-scanning system. The imagers cover a wavelength range of 350 - 1100 nm, with a spectral resolution of 5 nm. Because of their small weight of 750 g, the NH camera systems can easily be installed on a small UAV platform. We show the results from the analysis of data obtained by remote sensing applications including land vegetation and atmospheric monitoring from both ground- and airborne/UAV-based observations.

Application of remote sensing and GIS for anthropogenic vegetation monitoring

Comparison between actual and potential natural vegetation classifications has been done to identify impact of human activities on vegetation distribution over Asian region. The twelve monthly Normalized Difference Vegetation Index (NDVI) derived from NOAA/AVHRR data (1985-1997), together with climatic data, i.e. air temperature, and precipitation were processed by isoclass unsupervised and maximum likelihood algorithm to get the homogeneous spectral classes for land cover categorizing. Through classification trials, 68 clusters were found as the number of vegetation classes over this region. Moreover, the climatic characteristic value of each class, such as temperature, radiation cloudiness, precipitation, and elevation were extracted from available global dataset to determine the potential natural vegetation. By comparing those classifications, we realized, that India (Southern Asia), and some parts of China (Eastern Asia) were the center of land cover changing. This also appears in croplands of Kazakhstan, Indonesia, Mongolia, Thailand, Russia, Pakistan, Nepal, Myanmar (Burma), and Bangladesh.

Modeling three-dimensional forest structures to drive canopy radiative transfer simulations of bidirectional reflectance factor

ABSTRACT Three-dimensional (3-D) Monte Carlo-based radiative transfer (MCRT) models are usually used for benchmarking in intercomparisons of the canopy radiative transfer (RT) simulations. However, the 3-D MCRT models are rarely applied to develop remote sensing algorithms to estimate essential climate variables of forests, due mainly to the difficulties in obtaining realistic stand structures for different forest biomes over regional to global scales. Fortunately, some of important tree structure parameters such as canopy height and tree density distribution have been available globally. This enables to run the intermediate complexities of the 3-D MCRT models. We consequently developed a statistical approach to generate forest structures with intermediate complexities depending on the inputs of canopy height and tree density. It aims at facilitating applications of the 3-D MCRT models to develop remote sensing retrieval algorithms. The proposed approach was evaluated using field measurements of two boreal forest stands at Estonia and USA, respectively. Results demonstrated that the simulations of bidirectional reflectance factor (BRF) based on the measured forest structures agreed well with the BRF based on the generated structures from the proposed approach with the root mean square error (RMSE) and relative RMSE (rRMSE) ranging from 0.002 to 0.006 and from 0.7% to 19.8%, respectively. Comparison of the computed BRF with corresponding MODIS reflectance data yielded RMSE and rRMSE lower than 0.03 and 20%, respectively. Although the results from the current study are limited in two boreal forest stands, our approach has the potential to generate stand structures for different forest biomes.