# Establishing a Geological Knowledge Base for Braided River Deltas Using Google Earth
## 3 Results and Discussion
### Sedimentary Parameter Distribution Characteristics
#### 3.1.1 Wavelength Distribution  
Figure 4a shows Saloum delta's wavelength distribution, with 80% < 4500 m. Figure 4b displays Rufiji River's 80% wavelengths < 3000 m (30% in 2000-3000 m). Figure 4c indicates Lena River's 80% wavelengths < 8000 m (45% in 0-5000 m). Figure 4d shows Poyang Lake's 80% wavelengths < 4000 m (54% in 0-2000 m). Figure 4e illustrates Yukon-Kuskokwim delta's 80% wavelengths < 10,000 m. Figure 4f presents Orinoco's 80% wavelengths < 6000 m (36% in 2000-4000 m). Figure 4g shows Wax Lake's 80% wavelengths < 4000 m. Figure 4h displays Po River's 80% wavelengths < 4000 m (59% in 0-1000 m). Short-wavelength deltas (with 80% of wavelengths < 4000 m) mostly develop in proximal steep-slope environments. [PERSON] et al. indicated through numerical simulations and modern sedimentary analyses of the Rimaozhou delta in Poyang Lake that strong currents in proximal areas are rapidly distributed due to topographic constraints, forming short-wavelength deposits dominated by dendritic sandbars. The characteristic that 80% of their sandbody wavelengths are < 4000 m is highly consistent with the measured data  
Figure 4: Wavelength distribution and comprehensive data of eight groups of braided river deltas. \begin{table}
\begin{tabular}{c c c c c} \hline
**Delta Name** & **Latitude/Longitude** & **Area (km2)** & \
\begin{tabular}{c} **River Network Density** \\ **(km/km2)** \\ \end{tabular} &
\begin{tabular}{c} **Sedimentation Rate** \\ **(cm/year)** \\ \end{tabular} \\ \hline Wax Lake Delta & 29.27\({}^{\circ}\) N, 91.25\({}^{\circ}\) W & -11.26 & 5–8 & 0.5–1.0 \\ Yukon-Kuskokwim Delta & 61.45\({}^{\circ}\) N, 164.30\({}^{\circ}\) W & 129,500 & 2–3 & 0.3–0.5 \\ Lena River Delta & 72.30\({}^{\circ}\) N, 126.00\({}^{\circ}\) E & -33,600\({}^{\circ}\) & 4–6 & 1.0–1.5 \\ Po River Delta & 44.57\({}^{\circ}\) N, 12.22\({}^{\circ}\) E & 1450 & 6–8 & 0.2–0.5 \\ Poyang Lake Delta & 29.0\({}^{\circ}\) N, 116.18\({}^{\circ}\) E & 3500 & 3–5 & 0.8–1.2 \\ Orinoco Delta & 8.42\({}^{\circ}\) N, 60.30\({}^{\circ}\) W & 43,646 & 3–5 & 1.2–1.8 \\ Rufiji River Delta & 7.48\({}^{\circ}\) S, 39.24\({}^{\circ}\) E & Not specified & 2–4 & 0.6–1.0 \\ Saloum Delta & 13.84\({}^{\circ}\) N, 16.50\({}^{\circ}\) W & 1800 & 4–6 & 0.4–0.8 \\ \hline \end{tabular}
\end{table} 
Table 3: Key morphometric parameters of studied braided river deltas. from the Wax Lake and Po River deltas (80% of wavelengths! 4000 m, with 59% in the 0-1000 m interval), reflecting the coupled control of high sediment supply (annual sediment load! 10 million tons) and slopes! 0.3\({}^{\circ}\)[32]. As can be seen from Table 3, the Wax Lake and Po River deltas, which are typical short-wavelength deltas, also exhibit relatively high river network densities (5-8 km/km\({}^{2}\) and 6-8 km/km\({}^{2}\), respectively) compared to larger-sized deltas. This indicates that in addition to the sediment supply and slope, a high river network density may also contribute to the formation of short-wavelength features in these proximal environments. Long-wavelength deltas are associated with distal gentle-slope settings. The statistical analysis of the Lena River delta shows that 80% of wavelengths are! 8000 m, with 45% in the 0-5000 m interval, which is closely related to its massive distal supply (annual runoff of \(1.4\times 10^{12}\) m\({}^{3}\) and sediment load of 210 \(\times\) 10\({}^{6}\) tons) and gentle slopes, consistent with the \"distal long-flow-path promoting lateral sandbody extension\" model proposed by [PERSON] et al. [29]. Studies on the Ob River delta demonstrate that under gentle slopes (0.1-0.15\({}^{\circ}\)) and low-energy water conditions, distributary channels continuously prograde to form long-wavelength sandbodies extending 30-50 km, the wavelength distribution characteristics of which align with the sedimentary dynamic model established by [PERSON] et al. [33]. The 36% proportion of 2000-4000 m wavelengths in the middle Orinoco River reflects the control of high-frequency channel avulsions on sandbody stacking, consistent with [PERSON] et al.