\text { 1. } \quad \Delta S=P-(E+T+I+Q) \text { 2. Average precipitation }=\left(\Sigma P_{i} A_{i} / \Sigma A_{i}\right) \text { 3. } \quad Q_{p}=C I A \text { 4. }

f=f_{c}+\left(f_{0}-f_{c}\right) e^{-k t} F(t)=\int_{0}^{t} f d t=f_{c} t+\left[\frac{f_{0}-f_{c}}{k}\right]\left(1-e^{-k t}\right) \text { 8. } \quad H=\frac{p}{\gamma}+z+\frac{v^{2}}{2 g} \text { 9. } E=y+\frac{Q^{2}}{2 g A^{2}} \text { 10. } y_{c}=\left(\frac{q^{2}}{g}\right)^{1 / 3} \text { 11. } \frac{Q^{2}}{g}=\left(\frac{A^{3}}{B}\right) \text { 12. } \quad F_{r}=\frac{V}{\sqrt{g D}} \text { 12a. } \quad \frac{y_{2}}{y_{1}}=\frac{\sqrt{1+8 F_{r 1}^{2}}-1}{2} \text { 13. } Q=\frac{C_{n}}{n} A R_{h}^{2 / 3} S_{0}^{1 / 2} \text { 14. Area }=\frac{k}{2}\left[y_{0}+2\left(y_{1}+y_{2}+y_{3}+\ldots \ldots+y_{n-1}\right)+y_{n}\right] \text { 15. } \quad T_{R}=\frac{D}{2}+t_{p} \text { 16. } \quad Q_{p}=\frac{484 A}{T_{R}} \text { 17. } \quad t_{p}=\frac{l^{0.8}(S+1)^{0.7}}{1900 y^{0.5}} \text { 18. } \quad S=\frac{1000}{C N}-1 \text { 19. } \quad B=1.67 \mathrm{~T}_{\mathrm{R}} \text { 20. Snyder's method } \text { 21. } \quad t_{p}=C_{t}\left(L L_{c}\right)^{0.3} \text { 22. } \quad Q p=\frac{640 C_{p} A}{t_{p}} \text { 23. } \quad \mathrm{T}_{\mathrm{b}}=3=\mathrm{t}_{\mathrm{p}} / 8 \text { 24. } \quad I-Q=\frac{\Delta S}{\Delta t} \text { 25. } \frac{I_{1}}{2}+\frac{I_{2}}{2}-\frac{Q_{1}}{2}-\frac{Q_{2}}{2}=\frac{S_{2}-S_{1}}{\Delta t} \text { 26. } \quad S=K[x I+(I-x) Q] \text { 27. } \quad S_{2}-S_{1}=K\left[x\left(I_{2}-I_{1}\right)+(1-x)\left(Q_{2}-Q_{1}\right)\right] \text { 28. } \quad Q_{2}=C_{0} I_{2}+C_{1} I_{1}+C_{2} Q_{1} \text { 29. } \quad C_{0}=\frac{-K x+0.5 \Delta t}{D} \text { 30. } \quad C_{1}=\frac{K x+0.5 \Delta t}{D} \text { 31. } \quad C_{2}=\frac{K-K x-0.5 \Delta t}{D} \text { 32. } D=K-K x+0.5 \Delta t \text { 33. } \quad\left(I_{n}=I_{n+1}\right)+\left(\frac{2 S_{n}}{\Delta t}-Q_{n}\right)=\left(\frac{2 S_{n+1}}{\Delta t}+Q_{n+1}\right)