In large bowl, stir cake mix and flour. Reserve 1/3 cup cake mix mixture. To remaining mixture, add water, oil, eggs, cinnamon and nutmeg; beat with electric mixer on low speed 30 seconds, then on medium speed 2 minutes, scraping bowl occasionally. In medium bowl, stir carrots, raisins, walnuts and reserved cake mix mixture until coated. Stir into batter; pour into pan.