Basic Evaluation Units and Physical Structural Integrality in Riparian Zone Evaluation
г. I- -n Introduction....................................................................................................89
Bolin Fu
Guilin University Materials and Methods..................................................................................90
of Technology Study Area • Land-Cover Data and Ancillary Data • Field Data
Collection • Description of BEUs • PSI Indicators Derived from Remote Yeqiao Wang Sensing Data • Calculated PSI of the Riparian Zone
University of Rhode Island Results 96
Ying Li Riparian PSI • Accuracy Validation
Northeast Institute of Conclusions.....................................................................................................98
Geography and Agroecology References........................................................................................................98
Introduction
Riparian zones are narrow strips of land located along the banks of rivers, streams, and water networks. Riparian zones are widely acknowledged as an ecological transition zone of material and energy exchange between terrestrial and aquatic ecosystems (USDI Bureau of Land Management. Riparian Area Management, 1998; Tang et al., 2014). Riparian zones can provide a range of ecosystem functions and services, for example, bank stabilization and protection, water purification, reservoirs of biodiversity, wetland products, as well as recreation and tourism (Bennett 8c Simon, 2004; Ghermandi, et al., 2009; Hruby, 2009). Riparian zones are also a focus of human activities, such as urban expansion, agriculture, mining, grazing, erosion, and point- and non-point-source pollutions (Dixon et al., 2006; Ivits et al., 2009; Ranalli 8c Macalady, 2010). It is essential that riparian zones are managed appropriately to avoid degradation and damage that have become increasingly evident (Munne et al., 2003; Jansen et al., 2005; Ministry of Water Resources of the People’s Republic of China, 2010; Chen et al., 2012; Fernandez et al., 2014).
The physical structural integrality (PSI) characterizes riparian ecological conditions using indicators, for example, bank condition, riparian vegetation condition, and human intervention. Methodologies for assessing PSI of riparian zones have been developed to provide different evaluating indicators (Munne et al., 2003; Jansen et al., 2005; Innis et al., 2000; Barquin et al., 2011; Gonzalez del Tanago 8c Garcia de Jalon, 2011). Most of the methods are based on expert knowledge in selection of measuring sections and monitoring sites, then evaluating the PSI through field measurements. However, those methods are challenged in assessing long stretches of riparian zone, in particular vast regions and remote locations.
The evaluating methods have usually been concentrated on field measurements of a few hundred meters, which could be very laborious or even unpractical when attempting to evaluate an entire catchment or a long river corridor (Johansen et al., 2007). In addition, selection of measuring sections and sites might not be able to take into account simultaneously the representativeness, accessibility, and security, which made it difficult to fully characterize a riparian zone with site-based field data alone. Remote sensing techniques have been utilized to map indicators of riparian condition because of advantages in spatial extensiveness, noninvasiveness, and repetitive capability (Congalton et al„ 2002; Johansen & Phinn, 2006; Johansen et al., 2010a, 2010b). Those studies demonstrated that indicators such as stream- bed width, riparian zone width, riparian vegetation, and bank stability were important and feasible to extract from remote sensing data for condition assessment of riparian zones. However, evaluate riparian conditions using those indicators still remain to be examined.
This study evaluated the riparian condition of the Songhua River across the Northeastern Plain of China, using a series of indicators developed from 2,081 basic evaluation units (BEUs) (Fu et al., 2017). The specific objectives of this paper are to demonstrate the feasibility of the multimetric approach through comparisons with field measurements.
