Water Resources Research

Study area, LC, and distributions of validation sites (LC shows the dominant type in each 5 arc min grid). The abbreviations of basin names: EC, East Coast of the GOM; MARB: Mississippi-Atchafalaya River Basin; UMO: Upper Missouri; LMO: Lower Missouri; UMS: Upper Mississippi; LMS: Lower Mississippi; UOH: Upper Ohio; LOH: Lower Ohio; AR: Arkansas; RO: Red and Ouachita; TB: Texas Basin; RGB: Rio Grande Basin; and WSC: Western and Southern Coast of the GOM.

Digital photographs of all soil states for each soil type (SL, St, and SC). White boxes depict the 10 cm × 10 cm laser-scanned area.

Location of study sites within the Lower Mekong River Basin and their relationship to hydro-climatological controls potentially affecting river bank erosion. (a) Climatological July-August mean precipitation rates (shading in mm/day) and 925 hPa wind vectors (arrows) from Wang et al. []. The precipitation and wind climatology are derived from CMAP [Xie and Arkin, ] (1979–2000) and NCEP/NCAR reanalysis (1951–2000) data, respectively. The three boxes define major summer precipitation areas of the Indian tropical monsoon (5°–27.5°N, 65°–105°E), Western North Pacific (WNP) tropical monsoon (5°–22.5°N, 105°–150°E), and the East Asian subtropical monsoon (22.5°–45°N, 10°–140°E). Note the location of the Mekong Basin at the boundaries of these systems. (b) Detailed map of the Mekong Basin showing the locations of the Ang Nyay and Pakse study sites and major dams constructed since 1993. The locations of meteorological stations used in this study are also indicated.

Spatial distribution of (a) mean annual precipitation and (b) variability in precipitation across the country.

Track 1: Depth in meters. Track 2: Borehole geometry; average hole diameter in centimeters from PPC (orange dashed curve) with borehole washout/rugosity (pink shading). Track 3: Resistivity; bulk formation resistivity from AIT in ohmmeters at two DOIs—25 cm (solid black curve), 229 cm (solid red curve)—with the area between 229 cm and 25 cm resistivity curves shaded blue when the 229 cm DOI resistivity is greater than the 25 cm DOI resistivity and yellow when the 229 cm DOI resistivity is less than the 25 cm DOI resistivity. Track 4: NMR relaxation time distribution collected at 10.2 cm DOI with a support volume of 45.7 cm (waveforms); T2 distributions recorded as normalized amplitudes (higher waveform peaks [green shading] corresponding to higher amplitude) versus logarithmic relaxation time (from 0.5 to 10,000 ms) with T2ML (yellow curve) and T2 distribution cutoff time of 33 ms (dashed red line). Track 5: NMR determined porosity. Track 6: Formation quantitative mineralogy (dry weight fraction); displays the results from the ELAN integrated log analysis presented as the dry-weight fractions of mineral types—illite clay (gray with long black hatches), montmorillonite clay (brown with short black hatches), quartz (yellow with small black dots), calcite (aqua blue with brick pattern), orthoclase or other potassium feldspar (lavender black cross hatches), and other conductive minerals (gold with large black dots).

Aerial view of the Namaxia debris-dammed lake, Southern Taiwan, formed during Typhoon Morakot in August 2009 (source: Taiwan Forestry Bureau).